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Science MCQ (1 Marks)

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

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MCQ (1 Marks)

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50 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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