[1 Mark Questions]

Question 11 Mark

What is electroplating?

Answer

Electroplating is a method of coating one metal over another metal by passing an electric current.

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Question 21 Mark

Explain Wet Corrosion.

Answer

The corrosive action in the presence of moisture is called wet corrosion.
It occurs as a result of the electrochemical reaction of metal with water or an aqueous solution of salt or acids or bases.

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Question 31 Mark

Write a note on Dry corrosion.

Answer

The corrosive action in the absence of moisture is called dry corrosion.
It is the process of a chemical attack on a metal by corrosive liquids or gases such as $O _2, N_2, SO _2, H _2 S$ etc. in which $O _2$ is more reactive.
It occurs at high temperature

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Question 41 Mark

Why alloys are said to solid solutions?

Answer

Alloys can be considered solid solutions in which the metal with high concentration is solvent and other metals are solute.
Example: brass is a solid solution of zinc (solute) in copper (solvent).

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Question 51 Mark

What are the chemical properties of metals in terms of

valence electrons
Atomicity.

Answer

Valence electrons: Metals usually have 1, 2 or 3 electrons in their outermost shell.
Atomicity: Metals are usually monoatomic in their vapour state.

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Question 61 Mark

Mention the uses of iron.

Answer

Uses of iron:

Pig iron (Iron with 2 – 4.5 % of carbon): It is used in making pipes, stoves, radiators, railings, manhole covers and drain pipes.
Steel (Iron with < 0.25 % of carbon): It is used in the construction of buildings, machinery, transmission cables and T.V towers and in making alloys.
Wrought iron (Iron with 0.25 – 2 % of wrought carbon): It is used in making springs, anchors and electromagnets.

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Question 71 Mark

How will you convert copper into copper carbonate?

Answer

Copper reacts with oxygen in the presence of $CO _2$ and moisture to give copper carbonate.
$2 Cu + O _2+ CO _2+ H _2 O \rightarrow CuCO _3 . Cu ( OH )_2$ (Copper Carbonate).

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Question 81 Mark

Give a single term for each of the following:
(i) The process of extracting the ores from the Earth’s crust is called:
(ii) The rocky impurities associated with an ore is called:
(iii) The substance added to the ore to reduce fusion temperature:
(iv) Noble metals occur in this state:

Answer

Mining
Gangue or matrix
Flux
Native

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Question 91 Mark

Write the steps involved in metallurgical process.

Answer

A metallurgical process involves three main steps as follows:

Concentration or Separation of the ore: It is the process of removal of impurities from the ore.
Production of the metal: It is the conversion of the ore into metal.
Refining of the metal: It is the process of purification of the metal.

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Question 101 Mark

What is Electronegativity?

Answer

Electronegativity of an element is the measure of the tendency of its atom to attract the shared pair of electrons towards itself in a covalent bond.

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Question 111 Mark

What is an alloy?

Answer

An alloy is a homogeneous mixture of two or more metals or of one or more metals with certain non-metallic elements. The properties of alloys are often different from the component metals.

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Question 121 Mark

Define Ionisation energy.

Answer

Ionisation energy is the minimum energy required to remove an electron from a gaseous atom in its ground state to form a cation.

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Question 131 Mark

What is a covalent radius?

Answer

It is defined as half the distance between the nuclei of two covalently bonded atoms of the same element in a molecule.

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Question 141 Mark

Write the action of dil. $HCl$ and dil. $H _2 SO _4$ with iron.

Answer

(i) $Fe +2 HCl \rightarrow FeCl _2+ H _2 \uparrow$
(ii) $Fe + H _2 SO _4 \rightarrow FeSO _4+ H _2 \uparrow$

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Question 151 Mark

Define Atomic radius.

Answer

The atomic radius of an atom is defined as the distance between the centre of its nucleus and the outermost shell containing the valence electron.

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Question 161 Mark

What are the periodic properties?

Answer

Properties such as atomic radius, ionic radius, ionisation energy, electronegativity, electron affinity, show a regular periodicity and hence they are called periodic properties.

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Question 171 Mark

Explain the smelting process of iron in the Blast furnace.

Answer

The charge consisting of roasted ore, coke and limestone in the ratio 8 : 4 : 1 is smelted in a blast furnace by introducing it through the cup and cone arrangement at the top.

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Question 181 Mark

What is the modern periodic table?

Answer

The modem periodic table is a tabular arrangement of elements in rows and columns, highlighting the regular repetition of properties of the elements.

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Question 191 Mark

Give any two uses of aluminium.

Answer

Aluminium metal is a corrosion – resistant and a good conductor of heat. So it is used in making utensils.
Aluminium is used in welding as thermite and a very good reducing agent.

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Question 201 Mark

What is the action of Air and moisture on copper?

Answer

Copper gets covered with a green layer of basic carbonate in the presence of $CO _2$ and moisture.
$
2 Cu + O _2+ CO _2+ H _2 O \rightarrow CUCO _3 \cdot CU ( OH )_2
$

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Question 211 Mark

Define corrosion

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Question 221 Mark

Explain sacrificial protection.

Answer

Magnesium is more reactive than iron. When it is coated on the articles made of steel, it sacrifices itself to protect steel.

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Question 231 Mark

What is an amalgam? Give one example with its use.

Answer

An amalgam is an alloy of mercury with metals such as sodium, gold and silver.
Dental amalgam is an alloy of mercury with silver and tin and it is used in the dental filling.

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Question 241 Mark

What is dry corrosion or chemical corrosion?

Answer

The corrosive action in the absence of moisture is called dry corrosion. It is the process of a chemical attack on a metal by corrosive liquids or gases such as O2, N2, SO2, H2S etc… It occurs at high temperature, of all the gases mentioned above O2 is the most reactive gas to impart the chemical attack.

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Question 251 Mark

Mention the types of iron on the basis of carbon content.

Answer

Pig iron	Iron with 2 – 4.5% carbon
Wrought iron	Iron with < 0.25% carbon
Steel	Iron with 0.25 – 2% carbon

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Question 261 Mark

Explain the action of steam with iron.

Answer

$3 Fe +4 H _2 O \longrightarrow Fe _3 O _4+ H _2 \uparrow$
Iron (steam) Magnetic oxide Hydrogen

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Question 271 Mark

What are amalgams? How are they prepared?

Answer

An amalgam is an alloy of mercury with another metal.
Amalgams are formed by the metallic bonding with the electrostatic force of attraction between the electrons and the positively charged metal ions.

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Question 281 Mark

Explain the action of air with iron.

Answer

3Fe + 2O2 → Fe3O4 [Magnetic oxide (Black)].

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Question 291 Mark

What do you mean by Ferrous and Non-Ferrous alloys? Given an example for each.

Answer

Ferrous alloys : Contain iron as a major component.
Eg: Stainless steel, Nickel steel

Non-Ferrous alloys : These alloys do not contain iron as a major part.
Eg: Aluminium alloy, Copper alloy.

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Question 301 Mark

What happens when copper is treated with conc.HNO3 and with conc.H2SO4?

Answer

Conc.
$
Cu +4 HNO _3 \longrightarrow Cu \left( NO _3\right)_2+2 NO _2 \uparrow+2 H _2 O
$
Copper nitrate Nitrogen dioxide
$
Cu +2 H _2 SO _4 \longrightarrow CuSO _4+ SO _2 \uparrow+ H _2 O
$
Copper sulphate

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Question 311 Mark

Explain the action of dilute nitric acid with copper.

Answer

Copper reacts with dil. $HNO _3$ with the liberation of Nitric oxide gas.
$
3 Cu +8 HNO _3 \longrightarrow 3 Cu \left( NO _3\right)_2+2 NO \uparrow+4 H _2 O
$
Copper nitrate Nitric oxide

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Question 321 Mark

What is the action of heat on copper?

Answer

On heating at different temperatures in the presence of oxygen, copper forms two types of oxides $CuO , Cu _2 O$.
$2 Cu + O _2 \underset{\Delta}{\stackrel{\text { below } 1370 K }{\longrightarrow}} 2 CuO \text { Copper (II) oxide - black }$
$4 Cu + O _2 \underset{\Delta}{\stackrel{\text { abovel370K }}{\longrightarrow}} 2 Cu _2 O \text { Copper (I) oxide - red } $

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Question 331 Mark

Write a note on Aluminothermic process.

Answer

As reducing agent: Aluminium is a powerful reducing agent. When a mixture of aluminium powder and iron oxide is ignited, the latter is reduced to metal. This process is known as aluminothermic process.
$
Fe _2 O _3+2 Al \rightarrow 2 Fe + Al _2 O _3+\text { heat }
$

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Question 341 Mark

Prove that aluminium is a powerful reducing agent.

Answer

Aluminium is a powerful reducing agent When a mixture of aluminium powder and iron oxide is ignited, iron oxide is reduced to iron. This process is known as the aluminothermic process.
$
Fe _2 O _3+2 Al \longrightarrow 2 Fe + Al _2 O _3+\text { Heat }
$
Reducing agent

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Question 351 Mark

How does Aluminium react with caustic soda? Give an equation.

Answer

Aluminium reacts with caustic soda to give sodium meta aluminate with the liberation of $H _2$ gas.
$
2 Al +2 NaOH +2 H _2 O \longrightarrow 2 NaAlO _2+3 H _2 \uparrow
$
Sodium meta aluminate

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Question 361 Mark

How does Aluminium reacts with air?

Answer

Reaction with air: It is not affected by dry air. On heating at $800^{\circ} C$, aluminium bums very brightly forming it's oxide and nitride.
$4 Al +3 O _2 \rightarrow Al _2 O _3 \text { (Aluminium oxide) } $
$2 Al + N _2 \rightarrow 2 AIN \text { (Aluminium nitride) }$

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Question 371 Mark

Why does gold, silver and platinum occur in free state?

Answer

Gold, silver and platinum have low chemical reactivity and so they are found in the free state or in a native state.

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Question 381 Mark

Why the electron affinities of noble gases are zero?

Answer

Noble gases show no tendency to accept electrons because the outer 5 and p orbitals of noble gases are completely filled. No more electrons can be added to them and hence their electron affinities are zero.

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Question 391 Mark

What is slag? Give an example.

Answer

Slag is a fusible product formed when flux reacts with gangue during the extraction of metals.
Flux + gangue → slag
$CaO + SiO _2 \rightarrow CaSiO _3$

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Question 401 Mark

Elements a, b, c and d have the following electronic configurations

Answer

(a) $I s^2 2 s^2 2 p^6$
(b) $I s^2, 2 s^2, 2 p^6, 3 s^2, 3 p^1$
(c) $1 s^2, 2 s^2, 2 p^6, 3 s^2, 3 p^6$
(d) $I s^2, 2 s^2, I p^1$

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Question 411 Mark

Define metallurgy.

Answer

The various steps involved in the extraction of metals from their ores as well as refining of crude metals are collectively known as metallurgy.

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Question 421 Mark

Differentiate ore and mineral.

Answer

Ore	Mineral
1. Ores contain a large percentage of metal.	1. Minerals contain a low percentage of metal.
2. Ores can be used for die extraction of metals on a large scale readily and economically.	2. Metals cannot be extracted easily from minerals.
3. Bauxite $Al _2 O _3 \cdot 2 H _2 O$ is the ore of aluminium.	3. Clay $Al _2 O _3 .2 SiO .2 H _2 O$ is the mineral of aluminium.

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Question 431 Mark

Write the increasing order of radii of the following species.

Answer

(a) $Na ^{+}, Cl , Na , Cl ^{-}$
(b) Li, $Na , K , Rb$

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Question 441 Mark

What are minerals?

Answer

A mineral may be a single compound or a complex mixture of various compounds of metals found in the earth, e.g. Clay Al2O3. 2SiO2. 2H2O is the mineral of Aluminium.

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Question 451 Mark

What is the principle behind Froth floatation?

Answer

This process depends on the preferential wettability of the ore with oil (pine oil) and the gangue particles by water. Lighter ores, such as sulphide ores, are concentrated by this method. Eg: Zinc blende (ZnS).

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Question 461 Mark

Briefly write any four characteristics of a group in the periodic table.

Answer