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Science MCQ (1 Marks)

Physical and Chemical Changes · Jharkhand Board (JAC) STD 7 (Jharkhand - English Medium). 185 questions.

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MCQ (1 Marks)

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185 questions · auto-graded multiple-choice test.

MCQ 11 Mark
Dissolution of carbon dioxide gas in water is ________ change:
  • A
    Chemical
  • B
    Physical
  • ✓
    Both $A$ and $B$
  • D
    None of the above
Answer
Correct option: C.
Both $A$ and $B$

Dissolution of carbon dioxide gas in water is both physical and chemical change.
Carbon dioxide dissolves in water producing carbonic acid, also known as soda water.
$CO_2​ + H_2​O → H_2​CO_3​$
Due to dissolution, pressure change takes place. This implies a physical change.

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MCQ 21 Mark
Which of the following statements is incorrect for a chemical reaction?
  • ✓
    Heat may be given out but never absorbed.
  • B
    Sound may be produced.
  • C
    A colour change may take place.
  • D
    A gas may be evolved.
Answer
Correct option: A.
Heat may be given out but never absorbed.
Heat may be given out as well as absorbed during chemical reactions.
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MCQ 31 Mark
The reaction given below is a:
Copper sulphate+Iron→Iron sulphate+Copper
  • ✓
    Chemical change
  • B
    Physical change
  • C
    Both $A$ and $B$
  • D
    We cannot determined
Answer
Correct option: A.
Chemical change

Since the reaction involves the formation of two new substances iron sulphate and copper, it is a chemical change.

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MCQ 41 Mark
Classify the following as physical or chemical change. Metallic sodium is soft enough to be cut with a knife.
  • A
    Chemical
  • ✓
    Physical
  • C
    Both $A$ and $B$
  • D
    None of these
Answer
Correct option: B.
Physical

Physical Change:
It is a process in which the substance experiences a change in its physical properties like shape, size, colour, volume, appearance, state etc.
There is no change in its chemical composition.
When sodium metal is cut, there are only changes in its shape. Therefore, it is a physical change.

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MCQ 51 Mark
When you leave a piece of iron in the open for some time, it acquires a film of brownish substance. The substance is called:
  • A
    Acid
  • B
    Base
  • ✓
    Rust
  • D
    None of these
Answer
Correct option: C.
Rust
If you leave a piece of iron in the open area for a few days, it acquires a film of brownish substance, called rust.
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MCQ 61 Mark
Which of the following is a reversible change?
  • ✓
    Melting of ice
  • B
    Germination of seed
  • C
    Burning of matchstick
  • D
    Changing of milk into curd
Answer
Correct option: A.
Melting of ice
Melting of ice is a physical change in which substance changes its physical state but not properties.Hence it is a reversible change in which melted ice can freeze again by decrease in temperature.
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MCQ 71 Mark
Which is the formula of ozone?
  • A
    $Fe_2O_3$
  • B
    $Fe_3O_2$
  • C
    $O_2$
  • ✓
    $O_3$
Answer
Correct option: D.
$O_3$
D.  $O_3$
Explanation:
Medical $O_3,$ used to disinfect and treat disease, has been around for over $150$ years. Used to treat infections, wounds and multiple diseases, $O_3$'s effectiveness has been well-documented.
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MCQ 81 Mark
Consider The Following Sentences And Choose The Incorrect One:
  • A
    Cooking causes breakdown of complex molecules of carbohydrates, fats and proteins into smaller molecules.
  • ✓
    Rusting is a reddish$-$brown flaky substance that forms on the surface of any substances.
  • C
    Chemical change is permanent and irreversible change.
  • D
    Cooking is regarded as a decomposition reaction.
Answer
Correct option: B.
Rusting is a reddish$-$brown flaky substance that forms on the surface of any substances.
Rusting is a reddish$-$brown flaky substance that forms on the surface of iron objects after the process of rusting. Rest of all the statements are correct. Hence,
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MCQ 91 Mark
$2Mg + O_2​⟶:$
  • A
    $MgO$
  • ✓
    $2MgO$
  • C
    $MgO_2​$
  • D
    $2MgO_2$
Answer
Correct option: B.
$2MgO$
B.  $2MgO$
Explanation:
$2Mg + O_2⟶ 2MgO$
Magnesium is an alkaline earth metal with symbol Mg. Magnesium burns in air by taking oxygen from air to form magnesium oxide and is basic in nature.
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MCQ 101 Mark
Salt can be obtained by ___________ of sea water:
  • A
    Sublimation
  • B
    Cooling
  • ✓
    Evaporation
  • D
    Heating
Answer
Correct option: C.
Evaporation

On evaporation of seawater in shallow pools, salt along with impurities remain behind. Impured salt is taken in a tank and its saturated solution is prepared. In a saturated solution of salt, $HCl$ vapors are passed. Chloride ions being common to both, its concentration increases, and $NaCl$ gets precipitated which is free from impurities.

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MCQ 111 Mark
Which one of the following substances increase in weight by burning in air?
  • A
    Wood
  • ✓
    Magnesium
  • C
    Paper
  • D
    Candle
Answer
Correct option: B.
Magnesium

Magnesium increase in weight by burning in air.
When magnesium$(Mg)$ ribbon is burned in the air (with oxygen gas) it forms magnesium oxide $(MgO)$. This is a new compound formed according to the reaction,
$2Mg(s)​ + O_2(g) ​⟶ 2MgO(s)​$
If we measure the mass of magnesium oxide formed its mass is more than that of magnesium ribbon because the mass of oxygen gas is gets added with magnesium metal and also $MgO$ is formed as rust whose mass can be measure.
If we burned wood, paper, or candle in the air they form gaseous products, and hence their mass can not be measure.

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MCQ 121 Mark
Properties like size, shape, colour, state of a substance are
  • A
    Chemical properties
  • B
    Mental properties
  • ✓
    Physical properties
  • D
    Physicochemical properties
Answer
Correct option: C.
Physical properties
Properties such as shape, size, colour and state of a substance are called its physical properties.A physical change is generally reversible. In such a change no new substance is formed.
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MCQ 131 Mark
Physical changes like boiling do not make new materials and are easily reversed $e.g.$ by cooling, which causes $........$
  • ✓
    Condensation
  • B
    Reactants
  • C
    Reaction
  • D
    Colour
Answer
Correct option: A.
Condensation
Condensation: The change of a gas or vapor to a liquid, either by cooling or by being subjected to increased pressure. When water vapor cools in the atmosphere, for example, it condenses into tiny drops of water, which form clouds.
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MCQ 141 Mark
A change that affects iron articles and slowly destroys them is:
  • ✓
    Rusting
  • B
    Galvanisation
  • C
    Chemical change
  • D
    Crystallisation
Answer
Correct option: A.
Rusting
Rusting is oxidation of iron or iron objects. It takes place in the presence of air and moisture.
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MCQ 151 Mark
Chemical change involve:
  • A
    Change in shape
  • B
    Change in size
  • ✓
    Change in composition of atoms.
  • D
    None of these
Answer
Correct option: C.
Change in composition of atoms.
Chemical change involves a change in the composition of atoms which also means a new substance is formed.
Changes in shape and size are physical changes.
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MCQ 161 Mark
Solvent dissolve large amount of solute at$........$
  • A
    Room temperature
  • ✓
    Boiling temperature
  • C
    Freezing temperature
  • D
    Less than room temperature but more than freezing temperature
Answer
Correct option: B.
Boiling temperature
The solvent dissolves a large amount of solute at boiling temperature, $i.e$ an increase in temperature increases the solubility of the solute. As the temperature increases, the particles of the solid move faster which increases the chances that they will interact more with the solvent molecules.
As the temperature increases, the amount of solute that can be dissolved in a solvent increases generally is high at their individual boiling points.
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MCQ 171 Mark
Which of the following is true?
  • A
    Rusting will take place in absence of water.
  • B
    Rusting will take place in absence of air.
  • C
    Rusting will not take place in presence of water and air.
  • ✓
    None of the above.
Answer
Correct option: D.
None of the above.
Oxygen and water are the essential things required for rusting. Rusting will only take place in presence of water and air.
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MCQ 181 Mark
Ships suffer a lot of damage from rusting in spite of being painted because:
  • ✓
    Sea water contains many salts
  • B
    Sea water is bitter
  • C
    Sea water is sour
  • D
    Sea water is sweet
Answer
Correct option: A.
Sea water contains many salts
Ships are made of iron and a part of the ship always remain under sea water. The salts present in sea water increase the rate of rusting on ships and hence, ships suffer a lot of damage due to rusting.
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MCQ 191 Mark
Boojho Is Writing Some Sentences. Choose The Incorrect One And Help Him:
  • A
    Rusting of iron, photosynthesis and digestion of food are examples of chemical change.
  • B
    In order to protect iron from rusting a coating of zinc is deposited on its surface.
  • C
    Some substance cannot be obtained in pure state from their solution by crystallization.
  • ✓
    None of the above.
Answer
Correct option: D.
None of the above.
Here, all the statements are correct. Hence,
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MCQ 201 Mark
A coating of $........$ is deposited on iron bridges to prevent it from rusting:
  • A
    Platinum
  • ✓
    Zinc
  • C
    Silver
  • D
    Copper
Answer
Correct option: B.
Zinc
Metals like platinum, silver, and copper are at a lower position in the reactivity series and are less reactive than iron. If a protective coating of platinum, silver, and copper is applied to iron, they won't be able to prevent corrosion as they are less reactive. Moreover, using these metals will not be cost$-$effective.
But, zinc is placed above iron in the reactivity series and, so it is more reactive. It gets oxidized before the iron object and thus protects it from rusting. Also, it is cost$-$effective.
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MCQ 211 Mark
An example of a chemical change is:
  • A
    Formation of clouds
  • B
    Glowing of an electric light
  • ✓
    Dropping sodium into water
  • D
    Dissolving of salt in water
Answer
Correct option: C.
Dropping sodium into water
Chemical changes involve chemical reactions and the creation of new products. Typically, a chemical change is irreversible.
Examples are:
$1.$ Dropping sodium into water
$2.$ combustion $($burning$)$ of wood
$3.$ metabolism of food in the body
$4.$ cooking an egg
$5.$ digesting sugar with the amylase in saliva
$6.$ baking a cake
$7.$ electroplating a metal
$8.$ explosion of fireworks
$9.$ rotting bananas
$10.$ grilling a hamburger
$11.$ milk going sour
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MCQ 221 Mark
Paheli Is Writing Some Sentences, Choose The Correct Sentence And Help Her:
  • A
    Galvanization refers depositing a layer of zinc on iron.
  • B
    Souring of milk is a chemical change.
  • C
    Carbon dioxide turns lime water as milky.
  • ✓
    All the above.
Answer
Correct option: D.
All the above.
Here, all the statements are correct. Hence,
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MCQ 231 Mark
Rusting of iron is a chemical change because:
  • A
    It is temporary
  • B
    It can be cleaned and the original substance recovered
  • C
    Burning of matchstick
  • ✓
    A new substance is formed
Answer
Correct option: D.
A new substance is formed
A change in which one or more new substances are formed is known as chemical change. When the iron is exposed to air and moisture, rust formation takes place. Rust is nothing but iron oxide; a new substance formed out of the reaction. The colour of the surface of the iron also changes. Hence, rusting of iron is a chemical change.
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MCQ 241 Mark
Rusting can be prevented by:
  • A
    Coating the object with paint
  • B
    Coating the object with grease
  • C
    Galvanizing
  • ✓
    All of the above
Answer
Correct option: D.
All of the above
Hint: A red$-$colored coat formed on iron by the reaction of iron with oxygen in presence of air is called rust.
Explanation:
Rusting can be prevented by various methods.
$1.$ Coating the object with paint or grease can prevent rusting. The layer of paint and grease prevents the reaction of iron with air.
$2.$ Galvanization is the best method to prevent rusting. To protect the iron from rusting it is coated with zinc because zinc possesses a higher negative reduction potential than $Fe$ so zinc will oxidized before iron and protects iron from getting oxidized.
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MCQ 251 Mark
Which of the following is an example of chemical change?
  • A
    Filling up a balloon with hot air.
  • B
    Taking a glass of water and freezing it by placing it in the freezer.
  • ✓
    A plant collecting sunlight and turning it into food.
  • D
    Your dog ripping up your homework.
Answer
Correct option: C.
A plant collecting sunlight and turning it into food.
A plant collecting sunlight and turning it into food is a photosynthesis reaction which is an example of a photochemical reaction. This is a chemical change.
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MCQ 261 Mark
Identify the chemical change in the following:
  • A
    Freezing of water
  • ✓
    Rusting of iron
  • C
    Melting of wax
  • D
    Glowing of a bulb
Answer
Correct option: B.
Rusting of iron
Rusting of iron is chemical change while others are physical changes.
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MCQ 271 Mark
When a magnesium ribbon burns in air, the ash formed is dissolved in water:
  • ✓
    The solution of ash in water is basic in nature
  • B
    The solution of ash in water is acidic in nature
  • C
    The solution of ash in water is neutral in nature
  • D
    None of these
Answer
Correct option: A.
The solution of ash in water is basic in nature
On burning magnesium in air magnesium oxide is formed, when it is dissolved in water, a basic solution containing magnesium hydroxide is formed.
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MCQ 281 Mark
Pick out the chemical change from the following:
  • A
    Melting of ice
  • ✓
    Burning of coal in air
  • C
    Freezing of water
  • D
    None of the above
Answer
Correct option: B.
Burning of coal in air
The burning of coal in the air is a chemical change:
$\ce{C + O_2​ \rightarrow CO_2}$​
If there is insufficient oxygen then carbon monoxide is formed:
$\ce{2C + O_2​\rightarrow 2CO}$
Coal combustion releases nitrogen oxides, sulfur dioxide, particulate matter, mercury, and dozens of other substances known to be hazardous to human health.
Melting of ice and freezing of water are physical changes.
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MCQ 291 Mark
Paheli’s mother made a concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated.  This indicates a:
  • ✓
    Physical change that can be reversed.
  • B
    Chemical change that can be reversed.
  • C
    Physical change that cannot be reversed.
  • D
    Chemical change that cannot be reversed.
Answer
Correct option: A.
Physical change that can be reversed.
Crystallisation is a physical process and can be reversed.
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MCQ 301 Mark
Boojho Is Writing Some Sentences About Corrosion. Choose The Incorrect Statements And Help Him?
  • A
    Rusting is a slow oxidation process.
  • B
    Copper wires lose their shine and acquire green coating.
  • C
    Metal surface interacts with oxygen moisture and other gases present in air and slowly get coated with oxide.
  • ✓
    None of the above.
Answer
Correct option: D.
None of the above.
Here, all the statements are correct. Hence,
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MCQ 311 Mark
In Which Of The Following Statement Is Or Are Correct?
  • A
    Anodizing is the process in which metals like Aluminium, copper etc. are coated electrically to protect them from corrosion.
  • B
    Electroplating is the process where metal surface is covered with another metal by using electric current.
  • C
    Tinning is a process of giving a coating of molten tin to avoid corrosion.
  • ✓
    All the above.
Answer
Correct option: D.
All the above.
All the above.
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MCQ 321 Mark
Do You Know In Which Of The Following Sentences Is Or Are Incorrect?
  • A
    Cutting of a log of wood into pieces is a physical change.
  • B
    Limewater turns milky on passing $CO_2$ through it.
  • ✓
    Hydrogen gas are produced when acetic acid is added to a solution of a sodium hydrogen carbonate.
  • D
    Explosion of a firework is a chemical change.
Answer
Correct option: C.
Hydrogen gas are produced when acetic acid is added to a solution of a sodium hydrogen carbonate.
 When baking soda and vinegar are mixed together then a chemical change takes place and bubbles of carbon dioxide gas are formed along with some other substances.
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MCQ 331 Mark
The reddish brown deposit formed on iron nails kept in a solution of copper sulphate is:
  • A
    $\ce{Cu_2O}$
  • ✓
    $\ce{Cu}$
  • C
    $\ce{CuO}$
  • D
    $\ce{CuS}$
Answer
Correct option: B.
$\ce{Cu}$
Since according to reactivity series, iron is more reactive than copper so it will displace sulphate from copper sulphate.Copper is reddish brown in colour.
$\ce{Fe + CuSO_4​ \rightarrow FeSO_4​ + Cu}$
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MCQ 341 Mark
Which One Is A Physical Change?
  • A
    Melting of ic.
  • B
    Melting of wax.
  • C
    Formation of steam from water.
  • ✓
    All the above.
Answer
Correct option: D.
All the above.
Here, all the statements are related to physical change. Hence,
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MCQ 351 Mark
Which characteristic best describes a physical change?
  • A
    Composition changes
  • ✓
    Composition stays the same
  • C
    Form stays the same
  • D
    Mass is lost
Answer
Correct option: B.
Composition stays the same
Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes occur when objects or substances undergo a change that does not change their chemical composition.
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MCQ 361 Mark
Ozone layer protects us from harmful.
  • ✓
    Ultraviolet radiation.
  • B
    Infrared Radiation.
  • C
    Visible Radiation.
  • D
    Heat radiation.
Answer
Correct option: A.
Ultraviolet radiation.
Ultraviolet radiation.
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MCQ 371 Mark
The process of depositing a layer of one metal over another metal surface to protect it from rusting is called.
  • ✓
    Galvanization.
  • B
    Crystallization.
  • C
    Amalgamating.
  • D
    Neutralization.
Answer
Correct option: A.
Galvanization.
Galvanization.
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MCQ 381 Mark
Rusting is a special term, given to the corrosion of which metal?
  • A
    Zinc
  • B
    Copper
  • C
    Nickel
  • ✓
    Iron
Answer
Correct option: D.
Iron
Corrosion is a natural process, which converts a refined metal to a more chemically stable form, such as its oxide, hydroxide, or sulfide.
Rust is a general term for a series of iron oxides, usually, red oxides, formed by the reaction of iron with oxygen in the presence of water or air moisture.
Rusting is the common term for corrosion of iron and its alloys, such as steel. Many other metals undergo similar corrosion, but the resulting oxides are not commonly called rust.
Rusting is a special term for corrosion of iron.
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MCQ 391 Mark
Brown colour formation in an exposed apple after it's cut is:
  • A
    Physical change
  • ✓
    Chemical change
  • C
    Reversible change
  • D
    No change
Answer
Correct option: B.
Chemical change
The brown colour of the apple after cutting is due to the chemical change of the enzymes. When an apple is cut, oxygen is introduced into the exposed part and so, it changes colour. This is not a reversible change.
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MCQ 401 Mark
The process of obtaining Salt by the evaporation of sea water is known as $........$
  • ✓
    Crystallization.
  • B
    Sublimation.
  • C
    Galvanization.
  • D
    Amalgamation.
Answer
Correct option: A.
Crystallization.
Crystallization.
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MCQ 411 Mark
Which of the following is the most common solvent used for crystallization?
  • A
    Organic solvent $-$ benzene
  • ✓
    Water
  • C
    A salt solution
  • D
    Dilute solution of sulphuric acid
Answer
Correct option: B.
Water
The most common solvent used for crystallization is water. Water is capable of dissolving many substances compared to other liquids and is called the universal solvent.
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MCQ 421 Mark
Which Method Is Used To Prevent Rusting?
  • ✓
    Galvanization.
  • B
    Crystallization.
  • C
    Sedimentation.
  • D
    None of these.
Answer
Correct option: A.
Galvanization.
The process of depositing a layer of zinc on iron is known as “galvanization”. The iron pipes are galvanized to prevent rusting.
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MCQ 431 Mark
The process of obtaining salt by evaporation of seawater is known as:
  • ✓
    Crystallization
  • B
    Sedimentation
  • C
    Galvanization
  • D
    Amalgamation
Answer
Correct option: A.
Crystallization
It is known as crystallization $-$ because salt is obtained in crystal form.
Sedimentation is depositing solid as sediment.
Galvanization $-$ is the process of protecting iron$/$ metal by a coating of zinc.
Amalgamation $-$ is the formation of amalgam $($an alloy of mercury with another metal$).$
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MCQ 441 Mark
Corrosion is a chemical reaction that involves :
  • A
    The inside of the object changing from an element to a compound
  • ✓
    The surface of the object changing from an element to a compound
  • C
    Nothing happens
  • D
    The surface of the object changes from one element into another element
Answer
Correct option: B.
The surface of the object changing from an element to a compound
b.   The surface of the object changing from an element to a compoundExplanation:Corrosion is a natural process, which converts a refined metal to a more chemically stable form, such as its oxide, hydroxide, or sulfide.The corrosion process is a chemical change because two substances react together to form a new substance.When iron rusts, iron molecules react with oxygen molecules to make a compound called iron oxide.
The surface of an object is changing from an element to any compound such as oxide, hydroxide, sulfide etc.
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MCQ 451 Mark
Which of the following is a chemical change:
  • A
    melting of ice
  • B
    Boiling of water
  • ✓
    Rusting of iron
  • D
    Tearing a paper
Answer
Correct option: C.
Rusting of iron
When iron comes in contact with air and moisture it reacts with it and forms a brownish layer on its surface due to the formation of its oxides.
This is called rusting of iron. It is a chemical change since the new substance is formed.
Melting of ice, boiling of water, and tearing of paper are all physical changes.
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MCQ 461 Mark
Some pieces of chalk were taken and mixed with water. In this change, how many new substances are formed?
  • A
    $1$
  • B
    $2$
  • C
    $3$
  • ✓
    No new substance is formed
Answer
Correct option: D.
No new substance is formed

No new substances are formed. The chalk when mixed with water, no chemical reaction occurs. The chalk disperses in water which can be separated by filtration.

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MCQ 471 Mark
What type of protection is galvanising?
  • A
    Physical protection
  • B
    Sacrificial protection
  • ✓
    Physical and sacrificial protection
  • D
    One of the above.
Answer
Correct option: C.
Physical and sacrificial protection
Concept: Galvanizing is the process of applying a protective zinc coating to steel or iron to prevent rusting.
Explanation:
Zinc layer present on iron get oxidised as it is more reactive than iron and forms a layer of zinc oxide on it. As Zinc sacrifice itself to protect iron, it is physical and sacrificial protection.
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MCQ 481 Mark
Example of the physical change is:
  • A
    Respiration $($inhaling oxygen gas and exhaling carbon dioxide gas$)$
  • B
    Mixing vinegar and baking soda
  • ✓
    Evaporating water
  • D
    Burning fuel in your car
Answer
Correct option: C.
Evaporating water
In evaporation of water, only the physical state of water changes from liquid to gas, but not the chemical composition of water.
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MCQ 491 Mark
Two drops of dilute sulphuric acid were added to lg of copper sulphate powder and then small amount of hot water was added to dissolve it $($Step $I).$ On cooling, beautiful blue coloured eystals got separated $($Step $II).$ Step $I$ and Step $II$ are:
  • A
    Physical and chemical changes respectively.
  • B
    Chemical and physical changes respectively.
  • ✓
    Both physical change.
  • D
    Both chemical change.
Answer
Correct option: C.
Both physical change.

Step $I$ and Step $II$ are both physical change.

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MCQ 501 Mark
Which conditions are necessary for rusting?
  • A
    Oxygen
  • B
    Sunlight, water and metal
  • ✓
    Water, oxygen, a metal
  • D
    Metal and oxygen
Answer
Correct option: C.
Water, oxygen, a metal
Rusting takes place when there is contact between water, metal, and oxygen.
$\ce{4Fe + 3O_2​ + 2nH_2O \longrightarrow 2Fe_2O_3​. nH_2O}$
$($Iron$) ($oxygen$) ($water$) ($rust$)$
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MCQ 511 Mark
Chemical changes are $........:$
  • A
    Temporary, reversible and a new substance is produced
  • B
    Always accompanied by exchange of light
  • ✓
    Permanent, irreversible and a new substance is produced
  • D
    Never accompanied by exchange of light and heat energy
Answer
Correct option: C.
Permanent, irreversible and a new substance is produced
Chemical changes take place on the molecular level. A chemical change produces a new substance. It is a permanent and irreversible change.
Examples of chemical changes include combustion $($burning$),$ cooking an egg, rusting of an iron pan.
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MCQ 521 Mark
Boojho Is Writing About Physical Change. Read The Following Sentences And Choose The Incorrect One And Help Him:
  • A
    Evaporation and condensation sublimation are the example of physical change.
  • B
    There may be some changes in the physical properties such as state, colours, smell etc.
  • C
    The composition of the matter remains on unaltered.
  • ✓
    The physical change is usually permanent.
Answer
Correct option: D.
The physical change is usually permanent.
The physical change is usually temporarily
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MCQ 531 Mark
Adding sodium chloride to water is a:
  • ✓
    Physical change
  • B
    Chemical change
  • C
    Irreversible change
  • D
    None of these
Answer
Correct option: A.
Physical change
Physical changes are changes in the physical properties of substances. No new substances are formed in these changes.
The addition of sodium chloride to water does not result in the formation of any new substance, hence it is a physical change.
Also, sodium chloride can be reversed back to its original state by simple evaporation of water.
Therefore, it is a reversible change.
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MCQ 541 Mark
Which of the following is a chemical property of Aluminium?
  • ✓
    It corrodes with air.
  • B
    It is soft and malleable.
  • C
    It melts at $660^\circ C.$
  • D
    Its density is $2.70\ g/ cm^3.$
Answer
Correct option: A.
It corrodes with air.
It corrodes with air.
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MCQ 551 Mark
Physical change include change in:
  • A
    Texture
  • B
    Temperature
  • C
    Formation of bubbles
  • ✓
    Both $a$ and $b$
Answer
Correct option: D.
Both $a$ and $b$

The texture of a substance can differ with a physical change. For example, if a piece of wood was sanded, waxed, and polished, it would have a very different texture than it initially had like a rough piece of wood. Although, we cannot see temperature change, unless if a change of state is occurring, so it is a physical change.

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MCQ 561 Mark
What conditions are required for rusting to take place?
  • A
    Water only
  • B
    Oxygen only
  • ✓
    Water and oxygen
  • D
    Water and carbon dioxide
Answer
Correct option: C.
Water and oxygen
Rust is a general term for a series of iron oxides, usually, red oxides, formed by the reaction of iron with oxygen in the presence of water or air moisture. It is the common term for corrosion of iron and its alloys, such as steel. Both water and oxygen are required to form rust from metal iron.
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MCQ 571 Mark
Consider The Following Sentences And Choose The Correct One:
  • A
    Making sugar solution is a physical change.
  • B
    A physical change is generally reversible.
  • C
    Grinding of wheat grain changes its size, although it is a physical change.
  • ✓
    All the above.
Answer
Correct option: D.
All the above.
Here, all the statements are correct. Hence.
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MCQ 581 Mark
In which type of change , we observed alteration only in specific property of matter but not composition?
  • A
    Chemical change
  • ✓
    Physical change operator
  • C
    Both physical and chemical change
  • D
    None of the above
Answer
Correct option: B.
Physical change operator
In a physical change, we observed alteration in specific property of matter but not in composition. Physical change involves only a change in the physical state of matter. Composition and chemical properties remain same.
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MCQ 591 Mark
Which of the following statement is incorrect for a chemical reaction?
  • ✓
    Heat may be given out but never absorbed
  • B
    Sound may be produced
  • C
    A colour change may take place
  • D
    A gas may be evolved
Answer
Correct option: A.
Heat may be given out but never absorbed
Heat can be given out $−$ exothermic reaction.
Heat can also be absorbed $−$ endothermic reaction
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MCQ 601 Mark
Which of the following is not a physical property of a substance?
  • A
    Shape.
  • B
    Color.
  • C
    Density.
  • ✓
    Flammability.
Answer
Correct option: D.
Flammability.
Flammability.
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MCQ 611 Mark
Combustion is a ________________:
  • A
    Physical change
  • ✓
    Chemical change
  • C
    Both $A$ and $B$
  • D
    None of these
Answer
Correct option: B.
Chemical change

We get a new substance in combustion.
The reaction which gives a new substance is a chemical change.

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MCQ 621 Mark
What are the different conditions for a chemical reaction to take place?
  • A
    Close contact
  • B
    Solution form
  • C
    Heat
  • ✓
    All of the above
Answer
Correct option: D.
All of the above
$1.$ Close contact$—$ For a chemical reaction to take place the reactants should be brought in close contact $i.e.$ they should be mixed.
$2.$ Solution form$—$ Some substances react with each other only when they are mixed in the solution form.
$3.$ Heat$—$ Some reactants need to be heated to undergo a chemical change.
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MCQ 631 Mark
Iron pillar near the Qutub Minar in Delhi is famous for the following facts. Which of these facts is responsible for its long stability?
  • A
    It is more than $7m$ high.
  • B
    It weighs about $6000\ kg.$
  • C
    It was built more than $1600$ years ago.
  • ✓
    It has not rusted after such a long period.
Answer
Correct option: D.
It has not rusted after such a long period.
It has not rusted after such a long period.
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MCQ 641 Mark
Which is an example of a chemical change?
  • A
    The melting of ice
  • ✓
    The burning of wood
  • C
    The grindig of salt crystals powder
  • D
    The evaporation of water from a sea
Answer
Correct option: B.
The burning of wood
A change in which a new substance is formed is called a chemical change.
Examples of chemical change are digestion of food, ripening of fruit, burning of wood.
The burning of wood is a chemical change because it is always accompanied by the production of heat.
Melting of ice grinding of salt crystals to powder and evaporation of water from the sea are all physical changes because no new substances are formed.
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MCQ 651 Mark
Which of the following is not a physical change?
  • A
    Tearing a paper
  • B
    Bending an iron rod
  • C
    Freezing water into ice
  • ✓
    Curdling of milk
Answer
Correct option: D.
Curdling of milk
The tearing of paper is a physical change because it remains the same. Tearing a paper is a physical change because when the paper is torn only the appearance of the paper is changed and no new substance is formed. And freezing water into ice does not change its chemical constituents. Only phase changes from solid to liquid.
Cheese is made when an enzyme called rennet is added to milk. The rennet causes a chemical reaction where the milk solids curdle, separating themselves from the whey, or liquid portion of the milk
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MCQ 661 Mark
Magnesium hydroxide, obtained when Magnesium oxide is dissolved in water, is:
  • ✓
    Base.
  • B
    An acid.
  • C
    An indicator.
  • D
    A dissolving agent.
Answer
Correct option: A.
Base.
Base.
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MCQ 671 Mark
Which of the following is a feature of physical change?
  • A
    It is reversible
  • B
    It is temporary
  • C
    No new substance is formed
  • ✓
    All of these
Answer
Correct option: D.
All of these
Physical change refers to a change in which the molecules are rearranged but their internal composition remains same. It is Reversible, temporary and no new product formation takes place. Example$-$Tearing of paper, melting/freezing of water, cutting of trees, etc.
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MCQ 681 Mark
Insoluble impurities from solution during crystallization are removed by:
  • A
    Drying
  • ✓
    Filtration
  • C
    Heating
  • D
    Cooling
Answer
Correct option: B.
Filtration
Heating is the process of increasing the temperature of a body from its original temperature.
Cooling is the process of decreasing the temperature of a body from its original temperature.
Filtration is the process of separating small particles of solid matter from a liquid, by causing the liquid to pass through the pores of some substance, called a filter.
Insoluble impurities from solution during crystallization are removed by filtration as the insoluble solid particles passed through the filter.
Drying is the process of drying up the liquid present on any material by heating the material.
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MCQ 691 Mark
Iron rod turns red on heating. What kind of change is this?
  • ✓
    Physical change
  • B
    Periodic change
  • C
    Physical and chemical change
  • D
    Chemical change
Answer
Correct option: A.
Physical change
Physical changes are changes affecting the physical state of a chemical substance, but not its chemical composition. In the case of iron, when iron is heated it will get red colour but there is no change in its chemical form so it is not a chemical change, it is only a physical change.
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MCQ 701 Mark
Which of the following are true when milk changes into curd?
$i.$ Its state is changed from liquid to semi$-$solid.
$ii.$ It changes colour.
$iii.$ It changes taste.
$iv.$ The change cannot be reversed.
Choose the correct option.
  • A
    $(i)$ and $(ii).$
  • B
    $(ii)$ and $(iii).$
  • ✓
    $(i), (iii)$ and $(iv).$
  • D
    $(i)$ to $(iv).$
Answer
Correct option: C.
$(i), (iii)$ and $(iv).$
$(i), (iii)$ and $(iv).$
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MCQ 711 Mark
Which of the following is a chemical change?
  • ✓
    Boiling of eggs
  • B
    Evaporation of water
  • C
    Formation of snow
  • D
    Melting of wax
Answer
Correct option: A.
Boiling of eggs
Chemical changes result in the formation of new substances, and the changes that occur cannot be reversed. The heat from boiling an egg causes the egg's protein to change permanently in texture. It is a chemical change.
Evaporation of water, formation of snow and melting of wax are physical changes, as no new substances are formed.
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MCQ 721 Mark
Choose the most appropriate answer: Physical changes are:
  • A
    Permanent
  • B
    Periodic
  • ✓
    Temporary
  • D
    Irreversible
Answer
Correct option: C.
Temporary
Physical changes are temporary in nature. It does not affect the internal structure of a substance, only the molecules are rearranged. No new substance is formed.
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MCQ 731 Mark
Which of the following are true when milk changes into curd?
$i.$ Its state is changed from liquid to semi$-$solid.
$ii.$ It changes colour.
$iii.$ It changes taste.
$iv.$ The change cannot be reversed.
Choose the correct option.
  • A
    $(i)$ and $(ii).$
  • B
    $(ii)$ and $(iii).$
  • ✓
    $(i), (iii)$ and $(iv).$
  • D
    $(i)$ to $(iv).$
Answer
Correct option: C.
$(i), (iii)$ and $(iv).$
Colour of milk does not change after it convert into curds.
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MCQ 741 Mark
Which of the following is not a chemical change?
  • ✓
    Whipping eggs
  • B
    Burning wood
  • C
    Digestion
  • D
    All of above
Answer
Correct option: A.
Whipping eggs
Simply whipping of eggs does not produce any new substance. Hence, it is a physical change. But digestion and burning of wood result in the formation of new substances. Thus, they are physical changes.
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MCQ 751 Mark
Which of the following is $NOT$ a chemical change$?$
  • A
    Digestion of food
  • ✓
    Precipitation of rain and snow
  • C
    Rusting of iron
  • D
    Burning of paper
Answer
Correct option: B.
Precipitation of rain and snow
Precipitation is any product of the condensation of atmospheric water vapour that falls under gravity. The main forms of precipitation include drizzle, rain, sleet, and snow.
Precipitation occurs when a portion of the atmosphere becomes saturated with water vapour so that the water condenses and "precipitates". Here the water vapour in the air is changing from one form to another.
So precipitation of snow and rain is not a chemical change. In all the other options, a new substance is formed and the main substances cannot be reversed. So, they are chemical changes.
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MCQ 761 Mark
Which of the following is an example of physical change?
  • A
    A bud turning into a flower
  • B
    Rusting of iron
  • ✓
    Boiling of water
  • D
    Ripening of a tomato
Answer
Correct option: C.
Boiling of water
During boiling water forms steam $($water$)$ and thus there is no new substance formation. The chemical composition and properties of the original substance $($water$)$ is not changed. Therefore, boiling of water is a physical change.
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MCQ 771 Mark
Boiling water is a $........$ change because $........:$
  • ✓
    Physical, the gaseous water produced is chemically identical to the liquid water the process began with
  • B
    Physical, the water was disappeared
  • C
    Chemical, heat was required for the change
  • D
    Chemical, the process produced a gas
Answer
Correct option: A.
Physical, the gaseous water produced is chemically identical to the liquid water the process began with
Boiling water is a physical change because the gaseous water produced is chemically identical to the liquid water $i.e.$ both of them have the same molecular structure of the water.
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MCQ 781 Mark
Boojho Is Writing Some Sentences. Choose The Incorrect One And Help Him:
  • A
    Rusting of iron, photosynthesis and digestion of food are examples of chemical change.
  • B
    In order to protect iron from rusting a coating of zinc is deposited on its surface.
  • C
    Some substance cannot be obtained in pure state from their solution by crystallization.
  • ✓
    None of the above.
Answer
Correct option: D.
None of the above.
Here, all the statements are correct. Hence,
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MCQ 791 Mark
Stainless steel can protect iron from rusting as it contains:
  • A
    Tin
  • ✓
    Chromium
  • C
    Zinc
  • D
    Aluminium
Answer
Correct option: B.
Chromium

 Stainless steel can protect the iron from rusting or corrosion as it contains high percentages $(16-36\%)$ of chromium. This element is present in sufficient quantity that when exposed to oxidizing media it forms a thin, tightly adhering, and impervious oxide layer $($predominantly $CrO)$ that stops further corrosion.

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MCQ 801 Mark
When Magnesium ribbon is burnt in candle flame it burns with.
  • A
    Brilliant red light.
  • B
    Brilliant yellow light.
  • ✓
    Brilliant white light.
  • D
    Brilliant Green light.
Answer
Correct option: C.
Brilliant white light.
Brilliant white light.
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MCQ 811 Mark
Which of the following changes is accompanied by sound?
  • A
    Photosynthesis
  • B
    Spoilage of food
  • ✓
    Explosion of fireworks
  • D
    None of these
Answer
Correct option: C.
Explosion of fireworks
Burning of any substance is always accompanied by the production of heat, gas and light. Explosion of fireworks produce heat, light and sound, gas and smoke formed. The cut fruits and vegetables change its colour after some time.
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MCQ 821 Mark
Classify the following as physical or chemical properties. Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
  • ✓
    Chemical
  • B
    Physical
  • C
    Both $A$ and $B$
  • D
    None of these
Answer
Correct option: A.
Chemical

It is a chemical property as electron exchange takes place and new compound forms in this reaction.
$Zn + 2HCl → ZnCl_2​+ H_2$​

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MCQ 831 Mark
Baking of dough into bread is a kind of change:
  • A
    That can be reversed
  • ✓
    That cannot be reversed
  • C
    That can be reversed at every temperature
  • D
    Can't say
Answer
Correct option: B.
That cannot be reversed
It is an irreversible change.
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MCQ 841 Mark
What is the formula of rust?
  • ✓
    $Fe_2O_3$
  • B
    $Fe_3O_4$
  • C
    $FeO$
  • D
    None of these
Answer
Correct option: A.
$Fe_2O_3$
A.  $Fe_2O_3$
Explanation:
Iron metal does not burn in dry air even on strong heating. In moist air iron is slowly oxidised to give rust (iron oxide).
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MCQ 851 Mark
Which of the following is not true for a chemical change?
  • A
    New substances are formed
  • B
    They are irreversible
  • ✓
    Chemical properties of new substance are same
  • D
    Chemical properties of new substance are different
Answer
Correct option: C.
Chemical properties of new substance are same
$1.$ A chemical change is a permanent and not easily reversible.
$2.$ A chemical change results in an alteration in the composition of the molecules of the substance undergoing change and the formation of one or more new substances.
$3.$ The mass of the substance undergoing a chemical change usually changes.
$4.$ Heat is either absorbed or given out during a chemical change.
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MCQ 861 Mark
In Which Of The Following Statements Is Or Are Incorrect?
  • A
    Mixing of metals with other metal or nonmetals in molten from is called alloying.
  • B
    In an endothermic change heat is absorbed.
  • C
    Dissolution of sugar in water is a physical change we get back sugar and water by evaporation.
  • ✓
    Reaction between baking soda and vinegar oxygen is evolved.
Answer
Correct option: D.
Reaction between baking soda and vinegar oxygen is evolved.
Reaction between baking soda and vinegar oxygen is evolved.
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MCQ 871 Mark
Vacuum desiccator is used $........:$
  • ✓
    For drying crystals
  • B
    For purifying crystals
  • C
    For separation of crystals
  • D
    For the process of crystallisation
Answer
Correct option: A.
For drying crystals
Desiccators are an economical and reliable way to assure dry, dust$-$free storage and organization of humidity$-$sensitive products valuable reagents in crystalline form. Proper storage conditions can be optimized by selecting a desiccator size, shape, and control mechanism best suited for the application.
The lower compartment of the desiccator contains lumps of silica gel, anhydrous calcium chloride to absorb water vapor. The substance needing the desiccation is put in the upper compartment, on a glazed perforated ceramic plate. The ground glass rim of the desiccator lid must be greased with a thin layer of vacuum grease.
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MCQ 881 Mark
Take some clean iron nails and place them in the three test tubes prepared as under:
Test tube A: Contains boiled water and a thin layer of oil.
Test tube B: Contains dry air.
Test tune C: Testube half-filled with water.
All the test tubes are tightly closed after placing the nails. After some time what will you observe?
  • A
    Nails placed test tube $A$ rust.
  • B
    Nails placed test tube $B$ rust.
  • ✓
    Nails placed test tube $C$ rust.
  • D
    None of these
Answer
Correct option: C.
Nails placed test tube $C$ rust.

In test tubes $A$ and $B,$ corrosion of nails will not take place.
For corrosion to take place, air (or oxygen), water and iron, three should be in contact.
In test-tube $A,$ a layer of oil separates air from nails and boiled distilled water.
In test-tube $B,$ because the air is dry, hence no moisture is present which can cause rust.
In test-tube $C,$ rusting of nails takes place, as it has all the conditions necessary for rusting i.e. presence of air(oxygen) and moisture.

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MCQ 891 Mark
Growth of plants is a:
  • A
    Physical change
  • ✓
    Chemical change
  • C
    Both $A$ and $B$
  • D
    None of the above
Answer
Correct option: B.
Chemical change

The growth of plants is a chemical change, as its growth can not be reverted. And there are many chemical reactions such as photosynthesis which contribute to the growth of the plant.

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MCQ 901 Mark
Boojho Appeared In Class Test Where He Wrote Some Statements But He Confused To Know The Incorrect Statement. Would You Help Him To Know That?
  • A
    In a chemical change heat, light or both are generally given out or absorbed.
  • B
    Iron utensils when exposed to moist air get gradually coated with reddish brown coating called rust.
  • C
    A process of separating a pure substance in the form of crystals from the hot saturated solution by cooling is called crystallization.
  • ✓
    None of the above
Answer
Correct option: D.
None of the above
None of the above.
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MCQ 911 Mark
Large crystals of pure substances can be formed from their solutions during $........:$
  • ✓
    Crystallization
  • B
    Evaporation
  • C
    Expansion
  • D
    Contraction
Answer
Correct option: A.
Crystallization
Large crystals of pure substances can be formed from their solutions during crystallization.
For example, when hot acidic copper sulfate solution is cooled gradually, the crystals of copper sulfate are obtained.
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MCQ 921 Mark
Burning of wood is a $.........$ change:
  • A
    Reversible
  • B
    Physical
  • ✓
    Irreversible
  • D
    All of these
Answer
Correct option: C.
Irreversible
Answer should be irreversible. When wood is burnt a new substance is formed which cannot be reversed.
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MCQ 931 Mark
Rain formation is a:
  • A
    Chemical change
  • ✓
    Physical change
  • C
    No change takes place
  • D
    Gravitational phenomenon
Answer
Correct option: B.
Physical change
Rain formation is a physical change because it involves only a change in the physical state of water due to change in temperature but chemical properties remain same.
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MCQ 941 Mark
Chemical change are characterised by$..........$
  • ✓
    Formation of new substance
  • B
    Release of energy
  • C
    Absorption of energy
  • D
    Reversible
Answer
Correct option: A.
Formation of new substance
A chemical change is characterized by the formation of a new substance. Because during the formation of a new substance, Chemical composition changes.
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MCQ 951 Mark
A chemical change may involve:
  • A
    Change in colour only.
  • B
    Change in temperature only.
  • C
    Evolution of gas only.
  • ✓
    All of the these.
Answer
Correct option: D.
All of the these.
Chemical reactions may accompany change in colour, evolution of heat and gas etc.
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MCQ 961 Mark
Consider The Following Statements And Choose The Correct Ones:
  • A
    Corrosion of metals causes great economic loss.
  • B
    Corrosion of metals can be prevented if the contact between metal and air is cutoff.
  • C
    A process of giving a thin coating of zinc on Iron sheets to preventing rusting called galvanization.
  • ✓
    All the above.
Answer
Correct option: D.
All the above.
All the above.
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MCQ 971 Mark
The process of obtaining Salt by the evaporation of sea water is called.
  • ✓
    Crystallization.
  • B
    Neutralization.
  • C
    Galvanization.
  • D
    Amalgamation.
Answer
Correct option: A.
Crystallization.
Crystallization.
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MCQ 981 Mark
Which of the following statements is not correct?
  • A
    In a chemical change, color of the object may change.
  • ✓
    In a chemical change, heat will always be released.
  • C
    A chemical change always involves a physical change.
  • D
    Rusting of iron becomes faster when humidity is high.
Answer
Correct option: B.
In a chemical change, heat will always be released.
Signs of a chemical reaction include unexpected color change.
When copper reacts with the elements, it turns from its element color of reddish$-$brown to green.
So it is a chemical change.
Heat may or may not be released in a chemical reaction. It depends on the type of reaction.
Chemical changes cause a substance to change into an entire substance with a new chemical formula.
So its shape, size, etc also changes.
For rusting, the presence of both oxygen and water is essential.
The content of moisture in the air is high, which means if it is more humid, rusting becomes faster.
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MCQ 991 Mark
Which one of the following is a physical change?
  • A
    Rusting of iron.
  • B
    Combustion of magnesium ribbon.
  • C
    Burning of candle.
  • ✓
    Melting of wax.
Answer
Correct option: D.
Melting of wax.
Rusting, combustion and burning involve chemical changes.
Melting of wax is a physical change.
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MCQ 1001 Mark
Paheli’s Mother Made A Concentrated Sugar Syrup By Dissolving Sugar In Hot Water. On Cooling, Crystal Of sugar Got Separated. This Indicates A:
  • ✓
    Physical change that can be reversed.
  • B
    Chemical change that can be reversed.
  • C
    Physical change that cannot be reversed.
  • D
    Chemical change that cannot be reversed.
Answer
Correct option: A.
Physical change that can be reversed.
a.   Physical change that can be reversed.
Explanation:
Crystallization is a physical process and can be reversed.
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MCQ 1011 Mark
Paheli's mother made concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated. This indicates:
  • ✓
    Physical change that can be reversed
  • B
    Chemical change that can be reversed
  • C
    Physical change that cannot be reversed
  • D
    Chemical change that cannot be reversed
Answer
Correct option: A.
Physical change that can be reversed
This is a physical change as there is not any new substance formed having different chemical composition and properties. Only the state of the substance is changed during the process and it can be reversed.
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MCQ 1021 Mark
When magnesium ribbon burnt it produce:
  • A
    Magnesium hydroxide
  • ✓
    Magnesium oxide
  • C
    Magnesium chloride
  • D
    Magnesium sulphate
Answer
Correct option: B.
Magnesium oxide
When magnesium ribbon burns, it reacts with the oxygen present in the air and form a powdery ash called magnesium oxide.
$\ce{2Mg + O_2​\rightarrow 2MgO}.$
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MCQ 1031 Mark
Any characteristic that gives a sample of matter the ability$/$inability to undergo a change that alters its composition. It is called $.........$
  • A
    Physical change.
  • B
    Chemical change.
  • C
    Physical property.
  • ✓
    Chemical property.
Answer
Correct option: D.
Chemical property.
Chemical property.
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MCQ 1041 Mark
Which of these is the smallest particle?
  • A
    A molecule
  • ✓
    An atom
  • C
    A speck of dust
  • D
    A water drop
Answer
Correct option: B.
An atom
Atom is the basic unit of matter which cannot be broken down into independent particles
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MCQ 1051 Mark
Bathroom fittings are plated with $.........$ to prevent rusting:
  • A
    Zinc
  • B
    Copper
  • C
    Sulphate
  • ✓
    Chromium
Answer
Correct option: D.
Chromium
Bathroom fittings are plated with chromium to prevent rusting or corrosion. Metal objects made of iron and steel are usually electroplated with chromium.
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MCQ 1061 Mark
For protecting iron pipes from corrosion, they are coated with.
  • ✓
    Zinc.
  • B
    Copper.
  • C
    Aluminium.
  • D
    Silver.
Answer
Correct option: A.
Zinc.
Zinc.
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MCQ 1071 Mark
Your lab partner mixed two colorless solutions in the test tube. He sees no observable changes in the resulting mixture and is unable to detect any temperature change. Based on these observations, what type of change has taken place?
  • ✓
    Physical change
  • B
    Chemical change
  • C
    Periodic change
  • D
    None of the above
Answer
Correct option: A.
Physical change
In a periodic change, the events are repeated after regular intervals like day and night. In the given example, no such change is taking place.
When the two solutions are mixed, we cannot conclude it is a chemical change as no precipitate formation, no evolution of gas, no change in temperature, nor any other indication of a chemical change is seen. Thus the reaction can be considered to be reversible and, the change will be physical.
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MCQ 1081 Mark
What are the essential conditions for rusting to take place?
  • A
    Presence of pure water
  • ✓
    Presence of oxygen
  • C
    Presence of water
  • D
    Presence of oxygen alone is enough
Answer
Correct option: B.
Presence of oxygen
Rust is a general term for a series of iron oxides, usually, red oxides, formed by the reaction of iron with oxygen in the presence of water or air moisture.
So the presence of impure water and oxygen are required to form rust from metal iron.
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MCQ 1091 Mark
The change given below is an example of :
Hydrogen + Oxygen ⟶ Water
  • A
    Physical change
  • ✓
    Chemical change
  • C
    Both $A$ and $B$
  • D
    Neutralization reaction
Answer
Correct option: B.
Chemical change

Hydrogen and oxygen combine together to form water is a chemical change. When a new substance is formed the change is called a chemical change.

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MCQ 1101 Mark
Paheli Is Writing Some Statement Which Is Given By Her Teacher. Would You Help Him To Choose The Correct Statements?
  • A
    Stainless steel is an alloy of iron which does not rust easily.
  • B
    Cooking vessels made of copper and brass are given a coating of tin to avoid corrosion.
  • C
    Galvanization process where thin coating of zinc on iron sheets to prevent rusting.
  • ✓
    All the above.
Answer
Correct option: D.
All the above.
All the above.
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MCQ 1111 Mark
Rusting occurs when iron is exposed to:
  • ✓
    Oxygen and water
  • B
    Soil and rain
  • C
    Breeze and sunlight
  • D
    Salt water and clouds
Answer
Correct option: A.
Oxygen and water
When iron is in contact with water and oxygen, it rusts. If salt is present, for example in seawater or salt spray, the iron tends to rust more quickly, as a result of chemical reactions.
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MCQ 1121 Mark
Glowing of an electric bulb is a $........$ change:
  • ✓
    Physical
  • B
    Chemical
  • C
    Both physical and chemical changes
  • D
    None of these
Answer
Correct option: A.
Physical
When electricity is passed through the bulb $($tungsten$)$ the electrons in the atoms get excited and release the energy as light in terms of photons. So no chemical reaction is taking place. It is a physical reaction.
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MCQ 1131 Mark
How crystal of pure substances are obtained?
  • ✓
    By crystallization
  • B
    By chromatography
  • C
    By peptization
  • D
    By all these methods
Answer
Correct option: A.
By crystallization
The process of forming large crystals of pure substances from their solutions is known as Crystallization. The principle of crystallization is concerned with the thermodynamic conditions of crystallization and the kinetics of crystal nucleation and growth. Crystallization is the physical transformation of a liquid solution or gas to a crystal which is a solid with an ordered internal arrangement of molecules, ions or atoms.
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MCQ 1141 Mark
When Magnesium ribbon is burnt in oxygen, the product obtained is:
  • A
    Magnesium chloride.
  • B
    Magnesium sulphate.
  • ✓
    Magnesium oxide.
  • D
    Iron chloride.
Answer
Correct option: C.
Magnesium oxide.
Magnesium oxide.
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MCQ 1151 Mark
The formation of water is a reversible change. Identify the chemical equation of the formation of water:
  • A
    $H_2 ​+ 2O_2​ → 2H_2​O$
  • B
    $2H_2​+ O_2​→ H_2​O$
  • C
    $H_2​+ O_2​→ H_2​O$
  • ✓
    $2H_2​+ O_2 ​→ 2H_2​O$
Answer
Correct option: D.
$2H_2​+ O_2 ​→ 2H_2​O$
D.  $2H_2​+ O_2 ​→ 2H_2​O$
Explanation:
For a balanced equation, the number of atoms of each element must be the same on both sides of the equation. The number of atoms of hydrogen on the left-hand side of the equation is $4$ which is the same on the right-hand side of the equation. The number of atoms of oxygen on the left-hand side of the equation is $2$ which is the same on the right-hand side of the equation.
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MCQ 1161 Mark
When carbon dioxide is passed through lime water, it turns milky due to the formation of:
  • A
    Calcium hydroxide
  • ✓
    Calcium carbonate
  • C
    Calcium oxide
  • D
    None of these
Answer
Correct option: B.
Calcium carbonate
When carbon dioxide is passed through lime water, it turns milky due to formation of white precipitate in form of calcium carbonate.
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MCQ 1171 Mark
Paheli Is Writing Some Sentences About Chemical Change. Choose The Incorrect Statement And Help Her?
  • A
    Rusting and formation fermentation are the example of chemical change.
  • B
    In this change in which the composition and chemical properties of the substance get changes.
  • C
    This change is permanent and irreversible.
  • ✓
    None of the above.
Answer
Correct option: D.
None of the above.
Here, all the statements are correct. Hence,
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MCQ 1181 Mark
Chemical formula of rust is:
  • A
    $FeO$
  • B
    $Fe_3​O_4$
  • ✓
    $Fe_2O_3​.xH_2​O$
  • D
    $FeO.xH_2​O$
Answer
Correct option: C.
$Fe_2O_3​.xH_2​O$
C. $Fe_2O_3​.xH_2​O$
Explanation:
Chemical formula of rust is $Fe_2O_3​.xH_2​O$
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MCQ 1191 Mark
Galvanization is a process used to prevent rusting of which of the following:
  • ✓
    Iron
  • B
    Zinc
  • C
    Aluminum
  • D
    Copper
Answer
Correct option: A.
Iron
Layer of zinc is applied on iron surface in galvanization process to save it from rusting.
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MCQ 1201 Mark
Which one of the following is a chemical change?
  • A
    Twinkling of stars.
  • ✓
    Cooking of vegetables.
  • C
    Cutting of fruits.
  • D
    Boiling of water.
Answer
Correct option: B.
Cooking of vegetables.
Cooking of vegetables involves many chemical changes.
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MCQ 1211 Mark
Explosion of a fire work $($such as a cracker$):$
  • ✓
    Chemical
  • B
    Physical
  • C
    Both $A$ and $B$ possible according to condition
  • D
    Can not be predicted
Answer
Correct option: A.
Chemical
An explosion of a cracker is a chemical change because the explosive reactants are transformed into gaseous products along with heat, light, and sound which cannot be reversed.
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MCQ 1221 Mark
Conversion of milk into curd is:
  • A
    A physical property of milk
  • B
    A chemical property of milk
  • C
    A physical change
  • ✓
    A chemical change
Answer
Correct option: D.
A chemical change
When milk converts in curd the process is irreversible and a new substance with different properties is formed hence it is an example of a chemical change.
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MCQ 1231 Mark
Melting of wax is a _________ change:
  • ✓
    Physical
  • B
    Chemical
  • C
    Both $A$ and $B$
  • D
    None of the above
Answer
Correct option: A.
Physical

No new substances are formed when wax melts. This is a physical change. However, if the wax burns, it is a chemical change. The question here is associated with melting, and so the answer is 'physical' change.

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MCQ 1241 Mark
Sun tanning is a/ an:
  • A
    Physical change
  • ✓
    Chemical change
  • C
    Both $a$ and $b$
  • D
    None of the above
Answer
Correct option: B.
Chemical change

Sun tanning is a chemical change as vitamin $D$ is produced during tanning. As new products are formed during sun tanning, it is considered to be a chemical change.

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MCQ 1251 Mark
There Are Given Some Statement. In Which Of The Following Pair Is a Chemical Change?
  • A
    Ice melts on heating, iron rust in moist air.
  • B
    Common salt dissolve in water, pulses change on cooking.
  • ✓
    Milk into curd, germination of seeds.
  • D
    Ripening of fruits, melting of wax.
Answer
Correct option: C.
Milk into curd, germination of seeds.
Milk into curd and germination of seeds both are chemical changes. Hence,
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MCQ 1261 Mark
Adding salt to water makes it salty. Which of the following is true regarding this change?
  • A
    It is a chemical change because a new substance is formed
  • ✓
    It is a physical change because the original substances can be recovered
  • C
    It is a chemical change because there is exchange of heat
  • D
    It is a physical change because there is a slight change in colour
Answer
Correct option: B.
It is a physical change because the original substances can be recovered
Adding salt to water makes it salty. This is a physical change because the original substances can be recovered by evaporation. In a chemical change, substances cannot be recovered.
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MCQ 1271 Mark
Which of the following change is not a chemical change?
  • ✓
    Boiling of water
  • B
    Boiling of egg
  • C
    Burning of paper
  • D
    Burning of cloth
Answer
Correct option: A.
Boiling of water
The boiling of water is not a chemical change. If it boils for more time it changes to vapour state which is a physical change.
Whereas boiling of egg, burning of paper and cloth involves both physical and chemical change. The burning of paper and cloth forms ash.
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MCQ 1281 Mark
Neutralization is:
  • A
    A physical change
  • ✓
    A chemical change
  • C
    Sometimes physical and sometimes chemical change
  • D
    Neither a physical nor chemical change
Answer
Correct option: B.
A chemical change
Neutralization is a chemical change since it involves the formation of new compounds, salt and water.
Example: $\ce{HCl + NaOH \rightarrow NaCl + H_2O}$
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MCQ 1291 Mark
Turning milk into curd is a:
  • A
    Physical change.
  • B
    Physical property.
  • ✓
    Chemical change.
  • D
    Chemical property.
Answer
Correct option: C.
Chemical change.
Chemical change.
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MCQ 1301 Mark
Paheli mother made a concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated. This indicates a:
  • ✓
    Physical change that can be reversed
  • B
    Chemical change that can be reversed
  • C
    Physical change that cannot be reversed
  • D
    Chemical change that cannot be reverse
Answer
Correct option: A.
Physical change that can be reversed
This is a physical change as there is not any new substance formed having different chemical composition and properties. Only the state of the substance is changed during the process and it can be reversed.
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MCQ 1311 Mark
Classify the changes involved in the following process as physical or chemical changes: Dissolving sugar in water.
  • ✓
    Physical
  • B
    Chemical
  • C
    Both A and B possible according to condition
  • D
    Can not be predicted
Answer
Correct option: A.
Physical
Dissolving sugar in water in water is usually considered to be a physical change, in this process there is no new chemical species form.
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MCQ 1321 Mark
Dissolving sugar in water is an example of:
  • ✓
    Physical change
  • B
    Chemical change
  • C
    Neutralisation
  • D
    None of these
Answer
Correct option: A.
Physical change
Sugar dissolving in water is a physical change because in this change no new substance is formed and the process is reversible.
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MCQ 1331 Mark
What effect does salt have on the corrosion of iron?
  • A
    Absolutely none
  • ✓
    Speeds up the reaction
  • C
    Stops rust in it's tracks
  • D
    Gives off a different type of rust
Answer
Correct option: B.
Speeds up the reaction
Salt in water speeds up the reaction. This is because lots of dissociated ions are present in salt. As salt is a strong electrolyte and hence this tremendously accelerates corrosion in saltwater.
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MCQ 1341 Mark
Which of the following is a chemical change?
  • A
    Boiling of Water.
  • B
    Tearing of Newspaper.
  • ✓
    Cooking a vegetable.
  • D
    Freezing water into ice.
Answer
Correct option: C.
Cooking a vegetable.
Cooking a vegetable.
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MCQ 1351 Mark
A Chemical Change May Involve:
  • A
    Change in colour only.
  • B
    Change in temperature only.
  • C
    Evolution of gas only.
  • ✓
    All of these.
Answer
Correct option: D.
All of these.
Chemical reaction may accompany change in colour, evolution of heat and gas etc.
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MCQ 1361 Mark
A man painted his main gate made up of iron, to:
$i.$ Prevent it from rusting.
$ii.$ Protect it from the sun.
$iii.$ Make it look beautiful.
$iv.$ Make it dust free.
Which of the above statements is$/$are correct?
  • A
    $(i)$ and $(ii)$
  • B
    $(ii)$ and $(iii)$
  • C
    Only $(ii)$
  • ✓
    $(i)$ and $(iii)$
Answer
Correct option: D.
$(i)$ and $(iii)$
Iron gate does not need to be protected from sun. Paints cannot avoid dust.
To prevent rusting of Iron Gate, we do paint on it. Painting makes it beautiful.
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MCQ 1371 Mark
The process of forming large crystals of pure substances from their solutions is known as $.........:$
  • A
    Evaporation
  • B
    Purification
  • C
    Condensation
  • ✓
    Crystallisation
Answer
Correct option: D.
Crystallisation
The process of forming large crystals of pure substances from their solutions is known as Crystallization.
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MCQ 1381 Mark
Which among the following is a physical change?
  • A
    Burning of wood
  • B
    Ripening of fruit
  • ✓
    Cutting a log of wood in small pieces
  • D
    Cooking of food
Answer
Correct option: C.
Cutting a log of wood in small pieces
Cutting a log of wood in small pieces is a physical change. Burning of wood, Ripening of fruit, Cooking of food are chemical changes because a new substance is formed in them and they are not reversible.
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MCQ 1391 Mark
Two drops of dilute sulphuric acid were added to $1 g$ of copper sulphate powder and then small amount of hot water was added to dissolve it (Step $I).$
On cooling, beautiful blue coloured crystals got separated (Step II). Step $I$ and Step $II$ are:
  • A
    Physical and chemical changes respectively.
  • B
    Chemical and physical changes respectively.
  • ✓
    Both physical change.
  • D
    Both chemical change.
Answer
Correct option: C.
Both physical change.
Both physical change.
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MCQ 1401 Mark
A change in which a substance undergoes changes in its physical properties is called.
  • A
    Chemical change.
  • ✓
    physical change.
  • C
    No change.
  • D
    Biological change.
Answer
Correct option: B.
physical change.
physical change.
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MCQ 1411 Mark
In Which Of The Following Statement Are Incorrect?
  • A
    When a candle burns both physical and chemical change take place.
  • B
    Anaerobic bacteria digest animal waste and produce biogas.
  • C
    Ships suffer a lot of damage though they are not painted.
  • ✓
    Stretching of rubber band is not a physical change.
Answer
Correct option: D.
Stretching of rubber band is not a physical change.
Stretching of rubber band is a physical change.
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MCQ 1421 Mark
Iron pillar near the Qutub Minar in Delhi is famous for the following facts. Which of these facts is responsible for its long stability?
  • A
    It is more than $7 m$ high.
  • B
    It weighs about $6000kg.$
  • C
    It was built more than $1600$ yrs ago.
  • ✓
    It has no rust after such long period.
Answer
Correct option: D.
It has no rust after such long period.
Composition of the iron pillar make it resistant of rusting.
It has not rusted after such a long period.
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MCQ 1431 Mark
When carbon dioxide gas is passed through lime water, it turns lime water into $........$
  • ✓
    Milky.
  • B
    Blue.
  • C
    Silver.
  • D
    Golden.
Answer
Correct option: A.
Milky.
Milky.
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MCQ 1441 Mark
In Which Of The Following Sentences Is Incorrect?
  • ✓
    Cutting of log of wood into pieces is a chemical change.
  • B
    Iron pipes coated with zinc do not get rusted easily.
  • C
    Condensation of steam is not a chemical change
  • D
    The chemical name of baking soda is sodium hydrogen carbonate.
Answer
Correct option: A.
Cutting of log of wood into pieces is a chemical change.
Cutting of log of wood into pieces is a physical change.
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MCQ 1451 Mark
Dissolution of common salt or sugar in water is an example of:
  • ✓
    Physical change
  • B
    Chemical change
  • C
    Both $A$ and $B$
  • D
    None of the above
Answer
Correct option: A.
Physical change

Mixing salt or common salt with water results in a change in its physical state. Sugar and salt are solids. When added to water, they get dissolved and we can not see the solid particles anymore. But this does not change the nature of these substances, that is, no new substances are formed during the process. So, the dissolution of salt or sugar in water is a physical change.

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MCQ 1461 Mark
Which among the following is a physical change?
  • ✓
    Cutting a log of wood in small pieces
  • B
    Burning of wood
  • C
    Ripening of fruit
  • D
    Cooking of food
Answer
Correct option: A.
Cutting a log of wood in small pieces
Cutting a log of wood in small pieces is a physical change . Burning of wood, Ripening of fruit, Cooking of food are chemical changes because a new substance is formed in them and they are not reversible.
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MCQ 1471 Mark
Physical changes are $.........:$
  • ✓
    Temporary
  • B
    Permanent
  • C
    Irreversible
  • D
    Endothermic
Answer
Correct option: A.
Temporary
In a physical change, the substances are not altered chemically. No new products are formed.
A physical change can affect the size, shape or color of a substance but does not affect its composition. The substances may be changed to another phase $(i.e.$ gas, liquid, solid$)$ or separated or combined so physical changes are temporary.
Examples:
when ice melts when sulfur is mixed with iron filings. breaking a glass dissolving sugar in water
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MCQ 1481 Mark
Brown colour of the apple after cutting is:
  • A
    Physical change.
  • ✓
    Chemical change.
  • C
    No change.
  • D
    Biological change.
Answer
Correct option: B.
Chemical change.
Chemical change.
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MCQ 1491 Mark
Which of the following is true for ash, which is obtained by burning wood in the presence of oxygen?
  • A
    The properties of ash will be similar to wood
  • B
    The properties of ash will be similar to oxygen
  • ✓
    The properties of ash will be different from both wood and oxygen
  • D
    None of the above
Answer
Correct option: C.
The properties of ash will be different from both wood and oxygen
The burning of wood in the presence of oxygen produces ash. In this example, wood and oxygen undergo a chemical change to produce ash. The properties of ash are very different from wood or oxygen.
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MCQ 1501 Mark
In which type of change a new substance is formed?
  • A
    In physical change
  • ✓
    In chemical change
  • C
    In Both $A$ and $B$
  • D
    n neither of these
Answer
Correct option: B.
In chemical change
Chemical change does not forms new substance. There are two types of changes in matter namely physical and chemical change. Physical change is accompanied with change in physical properties of substances. This means they do not result in formation of new substances.
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MCQ 1511 Mark
Physical changes are:
  • ✓
    Those in which new substance is not formed.
  • B
    Those in which a new substance is formed.
  • C
    Always irreversible.
  • D
    None of the above
Answer
Correct option: A.
Those in which new substance is not formed.
In a physical change, the substance remains the same. A new substance is not formed. It is generally reversible. For instance, folding of paper.
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MCQ 1521 Mark
Formation of gas bubbles is $..........$
  • A
    A physical change.
  • B
    A physical property.
  • ✓
    A chemical change.
  • D
    A chemical property.
Answer
Correct option: C.
A chemical change.
A chemical change.
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MCQ 1531 Mark
What are the characteristics of a chemical change?
  • A
    Permanent
  • B
    Formation of new substances
  • C
    Absorption or release of heat, light
  • ✓
    All of above
Answer
Correct option: D.
All of above
A chemical change produces a new substance. The changes are permanent and mostly irreversible. Also, it involves absorption or release of energy in the form of heat or light.
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MCQ 1541 Mark
A Man Painted His Main Gate Made Up Of Iron, To
  • ✓
    Prevent it from rusting.
  • B
    Protect it from the Sun.
  • C
    Make it look beautiful.
  • D
    Make it dust free.
Answer
Correct option: A.
Prevent it from rusting.
Iron gate does not need to be protected from sun. Paints cannot avoid dust. To prevent rusting of iron gate, we do paint on it.
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MCQ 1551 Mark
A synthetic indicator phenolphthalein gives $...........$ colour in basic solution:
  • A
    Red
  • B
    Blue
  • ✓
    Pink
  • D
    Colorless
Answer
Correct option: C.
Pink
Phenolphthalein is often used as an indicator in acid-base titrations. It turns colourless in acidic solutions and pink in basic solutions. Phenolphthalein is slightly soluble in water and usually dissolved in alcohols for use in experiments.
It is a weak acid that can lose $H^+$ ions in solution. Phenolphthalein molecule is colourless and phenolphthalein ion is pink in colour. When a base is added to phenolphthalein, the molecule turns into ions leading to more ionization as $H^+$ ions are removed.
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MCQ 1561 Mark
Which of the following is a physical change?
  • A
    Rusting of Iron.
  • ✓
    Heating of Iron.
  • C
    Burning of Wood.
  • D
    Ripening of a fruit.
Answer
Correct option: B.
Heating of Iron.
Heating of Iron.
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MCQ 1571 Mark
Which of the following changes is not a physical change?
  • A
    Glowing of filament in bulb
  • ✓
    Combustion
  • C
    Boiling of water
  • D
    Sublimation
Answer
Correct option: B.
Combustion
Combustion represents a chemical reaction whereby the carbon compounds are converted into different chemicals like carbon dioxide and water vapor in presence of oxygen. So this is a chemical change.
The other options are physical changes as there is no change in the chemical composition of the substances in these processes.
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MCQ 1581 Mark
All of the following involve a chemical change at a particular temperature except :
  • A
    The formation of $HCl$ from $H_2$ and $Cl_2​$
  • B
    The color change when $NO$ is exposed to air
  • C
    The formation of steam from buring $H_2$​ and $CO_2​$
  • ✓
    The solidification of vegetable oil at low temperatures
Answer
Correct option: D.
The solidification of vegetable oil at low temperatures

All of the following involve a chemical change at a particular temperature except the solidification of vegetable oil at low temperatures.
It involves physical change. The physical state changes from liquid to solid.

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MCQ 1591 Mark
The freezing point of pure water is ____________:
  • A
    $100$ degree centigrade
  • B
    $50$ degree centigrade
  • C
    $20$ degree centigrade
  • ✓
    Zero degree centigrade
Answer
Correct option: D.
Zero degree centigrade

Freezing point is the temperature where a liquid converts into solid. Water converts into ice at zero degrees centigrade. So degree zero centigrade is the freezing point of water.

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MCQ 1601 Mark
What kind of change is undergone when an electric bulb glows?
  • ✓
    A physical change
  • B
    A chemical change
  • C
    Both physical and chemical changes
  • D
    A permanent change
Answer
Correct option: A.
A physical change
When an electric bulb glows, it is a physical change. As the light produced by the electric bulb is due to the heating effect of the conductor. Even though there is an occurrence of temperature change since no new substances are produced, it is considered to be a physical change.
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MCQ 1611 Mark
Crystallization takes place by the process of:
  • ✓
    Evaporation
  • B
    Condensation
  • C
    Sublimation
  • D
    Liquefication
Answer
Correct option: A.
Evaporation
Crystallization takes place by the process of evaporation.
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MCQ 1621 Mark
Which of these will cause a chemical change to occur?
  • A
    Grinding of wheat into flour
  • ✓
    Lighting of gas stove
  • C
    Evaporation of water from a lake
  • D
    Ringing of an electric bell
Answer
Correct option: B.
Lighting of gas stove
In gas burning, in a stove, the hydrocarbons from the fuel of the stove burns to form Carbon dioxide and Water vapour. As new substances are formed this is a chemical change.
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MCQ 1631 Mark
In Which Of The Following Sentences Are Incorrect?
  • A
    Chemical change is also called a chemical reaction.
  • B
    In a chemical change it is either evolved or absorbed.
  • C
    In a physical change no new substance is formed at all.
  • ✓
    None of the above.
Answer
Correct option: D.
None of the above.
Here, all the statements are correct. Hence,
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MCQ 1641 Mark
Common chemical changes are:
  • A
    Change in temperature
  • B
    Formation of precipitate
  • C
    Formation of bubbles
  • ✓
    All of above
Answer
Correct option: D.
All of above
A change in temperature is characteristic of a chemical change. When the reactants are mixed, the temperature change caused by the reaction is an indicator of a chemical change.
The formation of a precipitate may be one of the most common signs of a chemical reaction taking place. The formation of bubbles, or rather a gas, is another indicator of a chemical reaction taking place. When bubbles form, a temperature change could also be taking place.
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MCQ 1651 Mark
Which is a method to prevent rust?
  • A
    Crystallization
  • B
    Sedimentation
  • ✓
    Galvanisation
  • D
    None of these
Answer
Correct option: C.
Galvanisation
Galvanization is a method to prevent rust. The galvanization is a process of application of zinc coating on the iron and steel objects.
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MCQ 1661 Mark
A chemical change may involve:
  • A
    Change in colour only
  • B
    Change in temperature only.
  • C
    Evolution of gas only.
  • ✓
    All of the above.
Answer
Correct option: D.
All of the above.
All of the above.
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MCQ 1671 Mark
For rusting of iron to take place $..........$ are required:
  • A
    $O_2$​ and $CO_2$​
  • B
    $H_2O$ and $N_2$​
  • ✓
    $H_2O$ and $O_2$​
  • D
    $H_2O$ and $H_2$​
Answer
Correct option: C.
$H_2O$ and $O_2$​
Rusting of iron consists of the formation of hydrated oxide, $\ce{Fe_2O_3​. xH_2O}.$ It is an electrochemical process that requires the presence of water, oxygen, and an electrolyte.
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MCQ 1681 Mark
The change which is permanent and can not be measured by just reversing the condition is known as:
  • A
    Physical change
  • ✓
    Chemical change
  • C
    Both $A$ and $B$
  • D
    None of the above
Answer
Correct option: B.
Chemical change

A chemical change is a permanent change in the sense that it cannot be reversed by just reversing the conditions.

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MCQ 1691 Mark
A change in which the form of matter is altered but one substance is not transformed into another is called:
  • ✓
    Physical change
  • B
    Chemical change
  • C
    Biochemical change
  • D
    Photochemical change
Answer
Correct option: A.
Physical change
A physical change is a change of the physical state. They are usually reversible. The physical properties of a substance include such characteristics as shape $($volume and size$),$ color, texture, flexibility, density, and mass.
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MCQ 1701 Mark
An example of chemical change is:
  • A
    Water condensing on the outside of your cold beverage
  • B
    Bending a wire
  • C
    Slicing bread
  • ✓
    burning a candle
Answer
Correct option: D.
burning a candle
D burning a candle
Explanation:
The burning of the candle is permanent because once it is burnt it cannot be converted into the candle. A new product is also formed with a composition different from the candle. Hence it is a chemical change. Whereas the rest of the options represent the physical change.
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MCQ 1711 Mark
Galvanisation is a process used to prevent the rusting of which of the following?
  • ✓
    Iron.
  • B
    Zinc.
  • C
    Aluminium.
  • D
    Copper.
Answer
Correct option: A.
Iron.
Iron.
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MCQ 1721 Mark
Blue colour of the copper sulphate solution changes to Green colour when an iron nail is dropped into it due to the formation of:
  • ✓
    Iron sulphate.
  • B
    Copper chloride.
  • C
    Copper iron sulphate.
  • D
    Iron chloride.
Answer
Correct option: A.
Iron sulphate.
Iron sulphate.
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MCQ 1731 Mark
While forming crystals, it is important to:
  • A
    Evaporate to dryness to get purest possible crystals.
  • B
    Attach gas syringes to collect fumes.
  • ✓
    Not evaporate water of crystallization.
  • D
    Use high flames.
Answer
Correct option: C.
Not evaporate water of crystallization.
Crystals contain water of crystallization hence during the formation of crystals water of crystallization should not be evaporated. Also, crystallization is the process of the formation of crystals. Crystals are defined as highly organized molecules into a well$-$known structure.
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MCQ 1741 Mark
Which of the following would not be a physical change?
  • A
    Freezing water to make ice cubes.
  • B
    Melting gold to make jewellery.
  • ✓
    Burning gasoline in a lawn mower.
  • D
    Boiling water for soup.
Answer
Correct option: C.
Burning gasoline in a lawn mower.
Burning gasoline in a lawnmower is a chemical change. Here, a combustion reaction takes place. Freezing water to make ice cubes, melting gold to make jewellery and boiling water for soup are examples of physical change since, only a change in physical state takes place.
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MCQ 1751 Mark
Which of the following statements is incorrect for a chemical reaction?
  • ✓
    Heat may be given out but never absorbed.
  • B
    Sound may be produced.
  • C
    A colour change may take place.
  • D
    A gas may be evolved.
Answer
Correct option: A.
Heat may be given out but never absorbed.
Heat may be given out but never absorbed.
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MCQ 1761 Mark
Iron Pillar Near The Qutub Minar In Delhi Is Famous For The Following Facts. Which Of These Facts Is Responsible For Its Stability?
  • A
    It is more than $7$ metre height.
  • B
    It weighs about $6000 \ kg.$
  • C
    It was built more than $1600$ years ago.
  • ✓
    It has no rust after such long period.
Answer
Correct option: D.
It has no rust after such long period.

Composition of the iron pillar make it resistant of rusting. It has not rusted after such a long period.

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MCQ 1771 Mark
When magnesium is burnt in presence of air, the weight of magnesium:
  • ✓
    Increases
  • B
    Decreases
  • C
    Does not change
  • D
    Increases then decreases
Answer
Correct option: A.
Increases
When magnesium is burnt in the air, it reacts with oxygen in the air and forms magnesium oxide. Hence, the weight of magnesium increases.
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MCQ 1781 Mark
Rust forms on:
  • A
    Tin
  • B
    Copper
  • ✓
    Iron
  • D
    Lead
Answer
Correct option: C.
Iron
Rust is a reddish$-$ or yellowish$-$brown flaking coating of hydrated iron oxide that is formed on iron or steel by oxidation in the presence of moisture.
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MCQ 1791 Mark
Metal that is made by mixing iron with carbon, nickel and manganese is called.
  • ✓
    Stainless steel.
  • B
    German silver.
  • C
    Nichrome.
  • D
    Eureka.
Answer
Correct option: A.
Stainless steel.
Stainless steel.
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MCQ 1801 Mark
Which salt is obtained from the evaporation of sea water?
  • ✓
    Sodium chloride
  • B
    Magnesium chloride
  • C
    Calcium chloride
  • D
    Potassium chloride
Answer
Correct option: A.
Sodium chloride

The concentration of salt in sea water is 35 parts per thousand i.e $3.5\%$ of sea water's weight comes from dissolved salts.Thus, when the sea water evaporates, the salt that is left behind is sodium chloride.

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MCQ 1811 Mark
Which among the following is not a physical change?
  • A
    Melting of solids to liquids
  • B
    Vaporisation of liquids to gasses
  • ✓
    Liquefaction of gasses to liquids
  • D
    Decay of matter
Answer
Correct option: C.
Liquefaction of gasses to liquids
Melting, vapourisation and liquification all are pure physical changes where the chemical composition of the material does not change. But during the decay of matter, there occurs a permanent chemical change catalysed by living organism.
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MCQ 1821 Mark
Mohan Is Writing Some Sentences, Choose The Sentences Which Is Or Are Incorrect One:
  • A
    When carbon dioxide is passed through lime water, it turns milky due to the formation of calcium carbonate.
  • ✓
    The chemical name of baking soda is calcium carbonate.
  • C
    Two methods by which rusting of iron can be prevented are painting and galvanization.
  • D
    When a candle burns both physical and chemical change take place.
Answer
Correct option: B.
The chemical name of baking soda is calcium carbonate.
The chemical name of baking soda is sodium hydrogen carbonate. Here, all the statements are correct except option $[B].$ Hence
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MCQ 1831 Mark
Chemical changes are:
  • A
    Those that are reversible
  • ✓
    Those in which new substances are formed
  • C
    Those that do not release heat
  • D
    All of these
Answer
Correct option: B.
Those in which new substances are formed
Chemical changes are those in which new substances are produced. They are mostly irreversible and some do release heat while some absorb heat.
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MCQ 1841 Mark
When carbon dioxide is passed through lime water, then lime water becomes.
  • ✓
    Milky.
  • B
    Shiney.
  • C
    Silvery.
  • D
    Golden yellow.
Answer
Correct option: A.
Milky.
Milky.
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MCQ 1851 Mark
Which of the following might not tell a chemical change has taken place?
  • A
    Evolution of gas.
  • B
    Light is generated.
  • C
    Production of heat.
  • ✓
    Converting liquid into gas.
Answer
Correct option: D.
Converting liquid into gas.
Converting liquid into gas.
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