Text Book Back Questions and Answers - Chapter 8 Periodic Classification of Elements 10th Science Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

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Chapter 8 - Periodic Classification of Elements - 10th Science Guide Samacheer Kalvi Solutions

I. Choose the best answer.
Question $1 .$
The number of periods and groups in the periodic table are
(a) 6,16
(b) 7,17
(c) 8,18
(d) 7,18 .
Answer:
(d) 7,48 .

Question $2 .$
The basis of modern periodic law is:
(a) atomic number
(b) atomic mass
(c) isotopic mass
(d) number of neutrons
Answer:
(a) atomic number

Question 3.
________group contains the member of the halogen family.
(a) 17 th
(b) 15 th
(c) 18 th
(d) 16 th.
Answer:
(a) 17 th

Question $4 .$
_______is a relative periodic property.
(a) atomic radii
(b) ionic radii
(c) electron affinity
(d) electronegativity
Answer:
(d) electronegativity

Question $5 .$
Chemical formula of rust is
(a) $\mathrm{FeO}^{2} \mathrm{xH}_{2} \mathrm{O}$
(b) $\mathrm{FeO}_{4} \cdot \mathrm{xH}_{2} \mathrm{O}$
(c) $\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{XH}_{2} \mathrm{O}$
(d) $\mathrm{FeO}$.
Answer:
(c) $\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{XH}_{2} \mathrm{O}$

Question $6 .$
In the aluminothermic process the role of $\mathrm{Al}$ is
(a) oxidizing agent
(b) reducing agent
(c) hydrogenating agent
(d) sulphurising agent.

Answer:
(b) reducing agent

Question 7.
The process of coating the surface of metal with a thin layer of zinc is called:
(a) painting
(b) thinning
(c) galvanization
(d) electroplating
Answer:
(c) galvanization

Question 8.
Which of the following have inert gases 2 electrons in the outermost shell?
(a) $\mathrm{He}$
(b) $\mathrm{Ne}$
(c) Ar
(d) $\mathrm{Kr}$.
Answer:
(a) $\mathrm{He}$

Question $9 .$
Neon shows zero electron affinity due to:
(a) stable arrangement of neutrons
(b) stable configuration of electrons
(c) reduced size
(d) increased density
Answer:
(b) stable configuration of electrons

Question $10 .$
_______is an important metal to form an amalgam.
(a) Ag
(b) $\mathrm{Hg}$
(c) $\mathrm{Mg}$
(d) $\mathrm{Al}$.
Answer:
(b) $\mathrm{Hg}$

II. Fill in the blanks.
Question $1 .$
If the electronegativity difference between two bonded atoms in a molecule is greater than $1.7$, the nature of bonding is________
Answer:
Ionic bond.

Question 2.
________is the longest period in the periodical table.
Answer:
Sixth period.

Question $3 .$
________forms the basis of modem periodic table.
Answer:
Atomic number.

Question $4 .$
If the distance between two $\mathrm{Cl}$ atoms in $\mathrm{Cl}_{2}$ molecule is $1.98 \mathrm{~A}$, then the radius of the $\mathrm{Cl}$ atom is________
Answer:
$0.99 \AA$

Question $5 .$
Among the given species $\mathrm{A}^{-}, \mathrm{A}^{+}$, and $\mathrm{A}$, the smallest one in size is________
Answer:
$\mathrm{A}^{+}$.

Question 6 .
The scientist who propounded the modem periodic law is_______
Answer:
Henry Moseley.

Question 7.
Across the period, ionic radii_______ (increases,decreases)
Answer:
Decreases.

Question 8.
_______and_______ are called inner transition elements.
Answer:
Lanthanides and Actinides.

Question $9 .$
The chief ore of Aluminium is_______
Answer:
Bauxite $\left(\mathrm{Al}_{2} \mathrm{O}_{3} \cdot 2 \mathrm{H}_{2} \mathrm{O}\right)$

Question $10 .$
The chemical name of rust is_______
Answer:
Hydrated ferric oxide.

III. Match the following.
Question $1 .$

Answer:
$1-(b), 2-(\mathrm{e}), 3-(\mathrm{d}), 4-(\mathrm{c}), 5-(\mathrm{a})$

IV. True or False: (If false give the correct statement)
Question $1 .$
Moseley's periodic table is based on atomic mass.
Answer:
False.
Correct Statement: Moseley's periodic table is based on atomic number.

Question $2 .$
Ionic radius increases across the period from left to right.
Answer:
False.
Correct Statement: Ionic radius decreases across the period from left to right.

Question $3 .$
All ores are minerals, but all minerals cannot be called as ores.
Answer:
True.

Question $4 .$
Al wires are used as electric cables due to their silvery - white colour.
Answer:
False.
Correct Statement: Al wires are used as electric cables due to their good conductor of electricity.

Question $5 .$
An alloy is a heterogeneous mixture of metals.
Answer:
False.
Correct Statement: An alloy is a homogenous mixture of metals.

V. Assertion and Reason:
Answer the following questions using the data given below.
(i) $A$ and $R$ are correct, $R$ explains the $A$.
(ii) $\mathrm{A}$ is correct, $R$ is wrong.
(iii) $A$ is wrong, $R$ is correct.
(iv) $A$ and $R$ are correct, $R$ doesn't explain $A$.

Question $1 .$
Assertion: The nature of bond in HF molecule is ionic
Reason: The electronegativity difference between $\mathrm{H}$ and $\mathrm{F}$ is $1.9$.
Answer:
(i) $A$ and $R$ are correct, $R$ explains the $A$.

Question $2 .$
Assertion: Magnesium is used to protect steel from rusting.
Reason: Magnesium is more reactive than iron.
Answer:
(i) $\mathrm{A}$ and $\mathrm{R}$ are correct, $\mathrm{R}$ explains the $\mathrm{A}$.

Question 3 .
Assertion: An uncleaned copper vessel is covered with a greenish layer.
Reason: copper is not attacked by alkali
Answer:
(iv) $A$ and $R$ are correct, $R$ doesn't explain $A$.

VI. Short Answer Questions.

Question $1 .$
A is a reddish-brown metal, which combines with $\mathrm{O}_{2}$ at $<1370 \mathrm{~K}$ gives $\mathrm{B}$, a black coloured compound. At a temperature $>1370 \mathrm{~K}, \mathrm{~A}$ gives $\mathrm{C}$ which is red in colour. Find $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$ with reaction.
Answer:
(i) Reddish brown metal (A) is copper.
(ii) (A) reacts with $\mathrm{O}_{2}$ at bleow $1370 \mathrm{~K}$ gives Copper (II) oxide (B), which is black in colour. $2 \mathrm{Cu}+\mathrm{O}_{2} \underset{1370 k}{\stackrel{\text { below }}{\longrightarrow}} 2 \mathrm{CuO}$ (Copper (II) oxide) (B).
(iii) (A) reacts with $\mathrm{O}_{2}$ at above $1370 \mathrm{~K}$ gives Copper (I) oxide (C), which is red in colour.

Question $2 .$
$\mathrm{A}$ is a silvery - white metal. A combines with $\mathrm{O}_{2}$ to form $\mathrm{B}$ at $800^{\circ} \mathrm{C}$, the alloy of $\mathrm{A}$ is used in making the aircraft. Find $A$ and $B$.
Answer:
(i) Silver - white metal (A) is Aluminium.
(ii) (A) combines with $\mathrm{O}_{2}$ to form aluminium oxide at $800^{\circ} \mathrm{C}$.

(iii) Duralumin is the alloy of $\mathrm{Al}$, which is used to make aircraft.

Question $3 .$
What is rust? Give the equation for formation of rust.
Answer:
Rust is hydrated ferric oxide, $\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{xH}_{2} \mathrm{O}$. It is formed when iron is exposed to moist air.
$$
4 \mathrm{Fe}+3 \mathrm{O}_{2}+\mathrm{xH}_{2} \mathrm{O}>2 \mathrm{Fe}_{2} \mathrm{O}_{3} \times \mathrm{xH}_{2} \mathrm{O}
$$

Question $4 .$
State two conditions necessary for rusting of iron.
Answer:
Conditions for rusting of iron:
- The presence of water and oxygen is essential for the rusting of iron.
- Impurities in the iron, the presence of water vapour, acids, salts and carbon dioxide hasten to rust.
- Pure iron does not rust in dry and $\mathrm{CO}_{2}$ free air. It also does not rust in pure water, free from dissolved salts.

VII. Long Answer Questions
Question $1 .$
(a) State the reason for the addition of caustic alkali to bauxite ore during purification of bauxite.
(b) Along with cryolite and alumina, another substance is added to the electrolyte mixture. Name the substance and give one reason for the addition.
Answer:
(a) Naturally, Bauxite is not soluble in normal solvents. Therefore the addition of caustic alkali to bauxite plays an important role while extraction of aluminium. Caustic alkali dissolves bauxite forming soluble sodium meta aluminate while impurities remain insoluble and precipitate as red mud.

(b) Along with cryolite and alumina, another substance is added to the electrolyte mixture is Fluorspar. Adding of fluorspar lowers the fusion temperature of the electrolyte.

Question $2 .$
The electronic configuration of metal $\mathrm{A}$ is $2,8,18,1$. The metal $\mathrm{A}$ when exposed to air and moisture forms $\mathrm{B}$ a green layered compound. $\mathrm{A}$ with conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$ forms $\mathrm{C}$ and $\mathrm{D}$ along with water. $D$ is a gaseous compound. Find $A, B, C$ and $D$.
Answer:
(i) The electronic configuration of metal (A) is $2,8,18,1$. A is copper $(Z=29)$
(ii) (A) Copper exposed to air and moisture forms green layered compound (B) that is a copper carbonate.

(iii) Copper (A) reacts with conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$ to give copper sulphate (C) and Sulphur dioxide (D).

Question $3 .$
Explain the smelting process.
Answer:
Smelting (in a Blast Furnace): 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. There are three important regions in the furnace.

(a) The Lower Region (Combustion Zone): The temperature is at $1500^{\circ} \mathrm{C}$. In this region, coke bums with oxygen to form $\mathrm{CO}_{2}$ when the charge comes in contact with a hot blast of air.
$$
\mathrm{C}+\mathrm{O}_{2} \frac{1500^{\circ} \mathrm{C}}{\Delta} \mathrm{CO}_{2}+\text { Heat }
$$
It is an exothermic reaction since heat is liberated.
(b) The Middle Region (Fusion Zone): The temperature prevails at $1000^{\circ} \mathrm{C}$. In this region, $\mathrm{CO}_{2}$ is reduced to $\mathrm{CO}$.
$$
\mathrm{CO}_{2}+\mathrm{C} \frac{1000^{\circ} \mathrm{C}}{\Delta} 2 \mathrm{CO}-\text { Heat }
$$
Limestone decomposes to calcium oxide and $\mathrm{CO}_{2}$
$$
\mathrm{CaCO}_{3} \underset{\Delta}{\longrightarrow} \mathrm{CaO}+\mathrm{CO}_{2}-\text { Heat }
$$
These two reactions are endothermic due to absorption of heat. Calcium oxide combines with silica to form calcium silicate slag.
$$
\mathrm{CaO}+\mathrm{SiO}_{2} \rightarrow \mathrm{CaSiO}_{3}
$$

(c) The Upper Region (Reduction Zone): The temperature prevails at $400^{\circ} \mathrm{C}$. In this region carbon monoxide reduces ferric oxide to form a fairly pure spongy iron.
$\mathrm{Fe}_{2} \mathrm{O}_{3}+3 \mathrm{CO} \stackrel{400^{\circ} \mathrm{C}}{\longrightarrow} 2 \mathrm{Fe}+3 \mathrm{CO}_{2}$
The molten iron is collected at the bottom of the furnace after removing the slag.
The iron thus formed is called pig iron. It is remelted and cast into different moulds. This iron is called cast iron.

VIII. HOT Questions.
Question $1 .$
Metal A belongs to period 3 and group 13. A in red hot condition reacts with steam to form $B$. A with strong alkali forms $C$. Find $A, B$ and $C$ with reactions.
Answer:
(i) Metal (A) belongs to period 3 and group 13, is Aluminium (Al).
(ii) (A) $\mathrm{Al}$ in red hot condition reacts with steam to form Aluminium oxide (B).

(iii) Aluminium (A) reacts with strong alkali forms of sodium meta aluminate (C).

Question $2 .$
Name the acid that renders aluminium passive. Why?
Answer:
Dil. or cone. $\mathrm{HNO}_{3}$ does not attack aluminium, but renders $\mathrm{Al}$ passive due to the formation of oxide film on its surface.

Question 3 .
(a) Identify the bond between $\mathrm{H}$ and $\mathrm{F}$ in the HF molecule.
(b) What property forms the basis of identification?
(c) How does the property 7 vary in periods and in groups?
Answer:
(a) The nature of the bond in the HF molecule is ionic.
(b) Electronegativity.
(c) Along the period, from left to right in the periodic table the electronegativity increases because of the increase in the nuclear charge which in turn attracts the electrons more strongly. On moving down a group, the electronegativity of the elements decreases because of the increased number of energy levels.

I. Choose the best answer.
Question $1 .$
Which period contains only two elements?
(a) Second
(b) First
(c) Third
(d) Fifth.
Answer:
(b) First

Question $2 .$
The sixth period contains inner transition elements.
(a) 18
(b) 14
(c) 10
(d) 8
Answer:
(b) 14

Question $3 .$
Lanthanides and Actinides are called as
(a) Alkali metals
(b) Inner transition elements
(c) Transition elements
(d) Representative elements.
Answer:
(b) Inner transition elements

Question $4 .$
The number of valence electrons present in Halogens is:
(a) One
(b) Seven
(c) Zero
(d) Two

Answer:
(b) Seven

Question $5 .$
The distance between the two hydrogen nuclei of the molecule is $0.74 \AA$. So its covalent radius is
(a) $0.74 \AA$
(b) $0.99 \mathrm{~A}$
(c) $0.37 \AA$
(d) $7.4 \AA$.
Answer:
(c) $0.37 \AA$

Question $6 .$
Along the groups, atomic radius
(a) decreases
(b) increases
(c) decreases then increase
(d) no change.
Answer:
(b) increases.

Question 7.
Which one of the following elements will have the highest electronegativity?
(a) chlorine
(b) nitrogen
(c) caesium
(d) fluorine
Answer:
(d) fluorine

Question 8.
Electron affinity is measured in
(a) $\mathrm{kJ}^{-1}$
(b) $\mathrm{mol}^{-1}$
(c) $\mathrm{kJ} / \mathrm{mol}$
(d) $\mathrm{kJ} / \mathrm{mol}^{2}$
Answer:
(c) $\mathrm{kJ} / \mathrm{mol}$

Question $9 .$
Noble gases have_______ electron affinity,
(a) positive
(b) negative
(c) zero
(d) high.
Answer:
(c) zero

Question $10 .$
The element with positive electron gain enthalpy is:
(a) Hydrogen
(b) Sodium
(c) Argon
(d) Fluorine
Answer:
(b) Sodium

Question $11 .$
The mineral from which a metal can be readily and economically extracted on a large scale is said to be a / an
(a) Ore
(b) Flux
(c) Slag
(d) Gangue.
Answer:
(a) Ore

Question $12 .$
Flux + Gangue $\rightarrow$
(a) Mineral
(b) Matrix
(c) Slag
(d) Smog.
Answer:
(c) Slag

Question $13 .$
_______is used for anodizing process.

(a) 7
(a) Zinc
(b) iron
(c) Aluminium
(d) Tin
Answer:
(c) Aluminium

Question $14 .$
The ore which can be purified by gravity separation method is
(a) Haematite
(b) oxide ores
(c) sulphide ores
(d) both (a) and (b).
Answer:
(d) both (a) and (b).

Question $15 .$
The calcium silicate slag is formed in ______zone.
(a) combustion
(b) fusion zone
(c) reduction
(d) molten
Answer:
(b) fusion zone

Question $16 .$
Zinc blende is purified by
(a) Hydraulic method
(b) Magnetic separation method
(c) Froth floatation method
(d) Chemical method.
Answer:
(c) Froth floatation method

Question $17 .$
Bauxite ore is purified by
(a) Leaching process
(b) Hydraulic method
(c) Froth floatation method
(d) Magnetic separation method.
Answer:
(a) Leaching process

Question $18 .$
When copper reacts with dil. $\mathrm{HNO}_{3}$ it liberates________gas.
(a) $\mathrm{SO}_{2}$
(b) $\mathrm{NO}_{2}$
(C) $\mathrm{CO}_{2}$
(d) $\mathrm{NO}$
Answer:
(d) NO

Question $19 .$
Which metal process low melting point?
(a) Gallium
(b) Caesium
(c) Aluminium
(d) Copper.
Answer:
(a) Gallium

Question $20 .$
Which one of the following is not an ore of aluminium?
(a) Bauxite
(b) Haematite
(c) Cryolite
(d) Corundum.
Answer:
(b) Haematite

Question $21 .$
_______ is stored in Kerosene.
(a) Iron
(b) Silver
(c) Sodium
(d) Aluminium
Answer:
(c) Sodium

Question $22 .$
Electrolytic reduction of alumina into aluminium is
(a) Hall's process
(b) Alumino thermic process
(c) Baeyer's process
(d) Bessemerisation process.
Answer:
(a) Hall's process

Question $23 .$
In Hall's process, cathode used is
(a) Iron tank
(b) Graphite
(c) Pure alumina
(d) Iron tank linked with graphite.
Answer:
(d) Iron tank linked with graphite.

Question $24 .$
The metal oxides are usually _______ in nature.
(a) basic
(b) acidic
(c) amphoteric
(d) neither acidic nor basic
Answer:
(a) basic

Question $25 .$
A silvery-white metal is
(a) Aluminium
(b) Copper
(c) Iron
(d) Zinc.
Answer:
(a) Aluminium

Question $26 .$
Aluminium reacts with $\mathrm{NaOH}$ to give
(a) $\mathrm{Al}_{2} \mathrm{O}_{3}$
(b) $\mathrm{AlCl}_{3}$
(c) $\mathrm{NaAlO}_{2}$
(d) $\mathrm{Al}(\mathrm{OH})_{3}$
Answer:
(c) $\mathrm{NaAlO}_{2}$

Question $27 .$
Atoms of the elements belonging to the same group of periodic table will have:
(a) same number of protons
(b) same number of electrons in the valence shell
(c) same number of neutrons
(d) same number of electrons
Answer:
(b) same number of electrons in the valence shell

Question $28 .$
Chief ore of copper is

(a) $\mathrm{CuFeS}_{2}$
(b) $\mathrm{Cu}_{2} \mathrm{O}$
(c) $\mathrm{Cu}_{2} \mathrm{~S}$
(d) $\mathrm{CuSO}_{4}$
Answer:
(a) $\mathrm{CuFeS}_{2}$

Question $29 .$
Molecular formula for copper pyrites
(a) $\mathrm{Cu}_{2} \mathrm{O}$
(b) $\mathrm{Cu}_{2} \mathrm{~S}$
(c) $\mathrm{CuCO}_{3}$
(d) $\mathrm{CuFeS}_{2}$
Answer:
(d) $\mathrm{CuFeS}_{2}$

Question 30 .
The electronegativity of fluorine is:
(a) $4.0$
(b) 3
(c) $2.8$
(d) $2.1$
Answer:
(a) $4.0$

Question $31 .$
The second most abundant metal available next to aluminium is
(a) $\mathrm{Cu}$
(b) $\mathrm{Ag}$
(c) $\mathrm{Au}$
(d) $\mathrm{Fe}$.
Answer:
(d) Fe.

Question 32 .
Most important ore of iron is
(a) Haematite
(b) Magnetite
(c) Iron pyrite
(d) Cryolite.
Answer:
(a) Haematite

Question $33 .$
The volatile impurities present in haematite are:
(a) Carbon and Nitrogen
(b) Oxygen and Nitrogen
(c) Helium and Oxygen
(d) Sulphur and Phosphorus
Answer:
(d) Sulphur and Phosphorus

Question 34.
The solute present in brass is:
(a) copper
(b) zinc
(c) tin
(d) magnesium
Answer:
(b) zinc

Question 35 .
Which one of the following is used for making pressure cookers?
(a) Brass
(b) Magnalium
(c) Duralumin
(d) Nickel steel
Answer:
(c) Duralumin

Question $36 .$
Which is used as propeller?
(a) Stainless steel
(b) Nickel steel
(c) Brass
(d) Magnalium.
Answer:
(b) Nickel steel

Question $37 .$
Gold does not occur in the combined form. It does not react with air or water. It is in the _______ state.
(a) native
(b) combined
(c) complex
(d) molten.
Answer:
(a) native

Question $38 .$
Which of the following metal is not found in a free state?
(a) Ag
(b) $\mathrm{Au}$
(c) $\mathrm{Pt}$
(d) $\mathrm{Al}$.
Answer:
(d) A1.

Question $39 .$
Which one of the following does not react with copper?
(a) Oxygen
(b) $\mathrm{Conc} \cdot \mathrm{H}_{2} \mathrm{SO}_{4}$
(c) $\mathrm{NaOH}$
(d) $\mathrm{Conc} \cdot \mathrm{HNO}_{3}$
Answer:
(c) $\mathrm{NaOH}$

Question 40 .
An element which is an essential constituent of all organic compounds belongs to ______ group.
(a) 14 th
(b) 15 th
(c) 16 th
(d) 17 th.
Answer:
(a) 14 th

Question $41 .$
The highest ionization energy is exhibited by
(a) Halogens
(b) Alkaline earth metals
(c) Transition metals
(d) Nobel gases.
Answer:
(d) Nobel gases.

Question $42 .$
Which two elements of the following belongs to the same period? ( $\mathrm{Al}, \mathrm{Si}, \mathrm{Ba}, \mathrm{O}$ ).
(a) $\mathrm{Si}, \mathrm{Ba}$
(b) A1, Ba
(c) $\mathrm{A} 1, \mathrm{Si}$
(d) A1, O.
Answer:
(c) $\mathrm{Al}, \mathrm{Si}$

Question $43 .$
$98 \%$ pure copper and $2 \%$ impurities is called
(a) Matte
(b) Copper pyrites
(c) blister copper
(d) cuprite.
Answer:
(c) blister copper

Question $44 .$
______is used in making anchors and electromagnets.
(a) Steel
(b) Pig iron
(c) Cast iron
(d) Wrought iron.
Answer:
(d) Wrought iron.

Question 45 .
Which reagent does not react with iron?
(a) $\mathrm{Conc} . \mathrm{HNO}_{3}$
(b) $\mathrm{Conc}_{2} \mathrm{HO}_{4}$
(c) Steam
(d) $\mathrm{Dil}^{\mathrm{H}} \mathrm{HNO}_{3}$
Answer:
(a) Conc. $\mathrm{HNO}_{3}$

II. Fill in the blanks.
Question $1 .$
Matte is a mixture of______
Answer:
$\mathrm{Cu}_{2} \mathrm{~S}+\mathrm{FeS}$

Question $2 .$
Second group elements are called______
Answer:
Alkaline earth metals.

Question $3 .$
Ionisation energy is measured in ______ unit.
Answer:
$\mathrm{kJ} / \mathrm{mol}$

Question $4 .$
The ionisation energy ______ along the period.
Answer:
Increases.

Question $5 .$
______property, which predicts the nature of bonding between the atoms in a molecule.
Answer:
Electronegativity.

Question $6 .$
If the difference in electronegativity between two elements is $1.7$, the bond has ______and______
Answer:
$50 \%$ ionic character, $50 \%$ covalent character.

Question $7 .$
If the difference in electronegativity between two elements is less than $1.7$, the bond is considered to be______
Answer:
Covalent.

Question 8.
If the difference in electronegativity between two elements is greater than $1.7$, the bond is______
considered to be
Answer:
Ionic.

Question $9 .$
The process of extracting the ores from the earth's crust is called______
Answer:
Mining.

Question $10 .$
______is the main principle behind in Hydraulic method.
Answer:
Specific gravity.

Question $11 .$
Froth floatation process is preferable for______ ores.
Answer:
Lighter
(or)
Sulphide.

Question $12 .$
On heating in air, iron forms______
Answer:
$\mathrm{Fe}_{3} \mathrm{O}_{4}$

Question $13 .$
Iron reacts with Chlorine to form ______compound.
Answer:
Ferric chloride.

Question $14 .$
The corrosive action in the absence of moisture is called______
Answer:
Dry corrosion.

Question $15 .$
______technique used to renovate the Pamban bridge.
Answer:
Protective coating.

Question $16 .$
The atomic number is the number of______ in the nucleus or number of revolving around the nucleus in an atom.
Answer:
Protons, electrons.

Question $17 .$
The long form of periodic table is based upon the ______of elements.
Answer:
Electronic configuration.

Question $18 .$
In the periodic table, the horizontal rows are called and vertical columns are called______
Answer:
Periods, groups.

Question $19 .$
The modem periodic table has been divided into______ blocks known as______ blocks.
Answer:
Four, s, p, d,f

Question $20 .$
The______ of the elements in a period decreases from left to right and the atomic radii of the elements present in a group downwards.
Answer:
Atomic size, increases.

Question 21.
______period is the longest period and it contains______ elements.
Answer:
Seventh, 32 .

Question $22 .$
In the periodic table, there are______ groups and ______periods.
Answer:
18,7 .

Question $23 .$
Metals like $\mathrm{Ti}, \mathrm{Cr}, \mathrm{Mn}, \mathrm{Zr}$ find their application in the manufacturing of defence equipment called______
Answer:
Strategic metals.

Question $24 .$
The metal______ plays a vital role in nuclear reactions releasing nuclear energy and used in nuclear weapons.
Answer:
Uranium.

Question $25 .$
Copper, silver and gold are called______ as they are used in making ______and______
Answer:
Coinage metals, coins and jewellery.

Question $26 .$
Purity of gold is expressed in______ and______ is pure gold.
Answer:
Carats, 24 - carat gold.

Question $27 .$
______is an ore of aluminium and______ is its mineral.
Answer:
Bauxite, clay.

Question $28 .$
All ______cannot be called as ores but all______ are minerals.
Answer:
Minerals, ores.

Question $29 .$
The process of extracting the ores from the earth's crust is called______
Answer:
Mining.

Question 30 .
The rocky impurity associated with the ore is called______ or______
Answer:
Gangue, matrix.

Question $31 .$
______is a substance added to the ore to reduce the fusion temperature and to remove impurities.
Answer:
Flux.

Question $32 .$
______is the process of reducing the roasted metallic oxide to metal.
Answer:
Smelting.

Question 33 .
Slag is the fusible product formed when______ reacts with______ during the extraction of metals.
Answer:
Flux, gangue

Question $34 .$
The temperature applied in Hall's process is______ and the voltage used in______
Answer:
$900-950^{\circ} \mathrm{C}, 5-6 \mathrm{~V}$

Question 35 .
______is used in making manhole covers and drain pipes and______ is used in making transmission cables and T.V. towers.

Answer:
Pig iron, steel.

Question $36 .$
______is defined as the slow and steady destruction of a metal by the environment.
Answer:
Corrosion.

Question $37 .$
______is a process of coating zinc on iron sheets by using electric current.
Answer:
Galvanization.

III. Match the following.
Question $1 .$

Answer:
$$
i-c, i i-e, \text { iii }-d, i v-b, v-a \text {. }
$$

Question $2 .$

Answer:

$i-d, i i-c, i i i-b, i v-a .$

Question 3 .

Answer:
$$
i-b, \text { ii }-d, \text { iii }-a, i v-c \text {. }
$$

Question $4 .$

Answer:
$$
\mathrm{i}-\mathrm{c}, \mathrm{ii}-\mathrm{a}, \mathrm{iii}-\mathrm{d}, \mathrm{iv}-\mathrm{b} \text {. }
$$

Question $5 .$

Answer:

$i-b, i i-a, i i i-d, i v-c$.

Question $6 .$

Answer:
$$
i-d, i i-c, i i i-b, i v-a \text {. }
$$

Question $7 .$

Answer:
$$
i-b, i i-c, i i i-a, i v-d .
$$

Question $8 .$

Answer:
$$
i-b, i 1-d, i 1 i-a, i v-c \text {. }
$$

Question $9 .$

Answer:

Question 10 .

Answer:

IV. State whether true or false. If false, give the correct statement.
Question 1.
First period contains only one element.
Answer:
False.
Correct Statement: First period contains two elements.(Hydrogen \& Ftelium)

Question 2.
The valency of all alkali metals is one.
Answer:
True.

Question $3 .$
Noble gases are more reactive.
Answer:
False.
Correct Statement: Noble gases are less reactive.

Question $4 .$
The atomic radius decreases from $\mathrm{Li}$ to $\mathrm{B}$ ?
Answer:
True.

Question $5 .$
As the positive charge increases, the size of the cation also increases.
Answer:
False.
Correct Statement: As the positive charge increases, the size of the cation also decreases.

Question $6 .$
Copper pyrite ore is concentrated by gravity separation method.

Answer:
False
Correct Statement: Copper pyrite ore is concentrated by froth floatation process.

Question $7 .$
Aluminium alloyed with gold and silver for making coins and jewels.
Answer:
False.
Correct Statement: Copper alloyed with gold and silver for making coins and jewels.

Question $8 .$
The corrosive action in the presence of moisture is called wet corrosion.
Answer:
True

Question $9 .$
The physical and chemical properties of elements are the periodic function of their atomic numbers
- modern periodic law.
Answer:
True.

Question 10 .
The long form of periodic table consists of horizontal rows called groups and vertical columns called periods.
Answer:
False.
Correct statement: The long form of periodic table consists of horizontal rows called periods and vertical columns called groups.

Question $11 .$
The first period in the periodic table is the shortest period and contains 8 elements from Lithium to Neon.
Answer:
False.
Correct statement: The first period in the periodic table is the shortest period and contains 2 elements Hydrogen and Helium.
(OR)
The second period in the periodic table is the short period and contains 8 elements from Lithium to Neon.

Question $12 .$
The sixth period in the periodic table is the longest period and contains 32 elements.
Answer:
True.

Question $13 .$
Group 1, 2 and $13-18$ are called normal elements.
(or)
Main group elements.
(or)
Representative elements.
Answer:
True.

Question $14 .$
The atomic size of the elements in a period increases from left to right.
Answer:
False.
Correct statement: The atomic size of the elements in a period decreases from left to right.

Question $15 .$
In a period, the metallic character of the element increases while their non-metallic character decreases.
Answer:
False.
Correct statement: In a period, the metallic character of the element decreases while their nonmetallic character increases.

Question $16 .$
The last element authenticated by IUPAC is $\mathrm{Cn} 112$ [Copemicium].
Answer:
True.

Question $17 .$
Silver was the first metal to be used in making utensils and weapons.
Answer:
False.
Correct statement: Copper was the first metal to be used in making utensils and weapons.

Question $18 .$
The strategic metals such as copper, silver and gold are used in the manufacturing of defence equipment.
Answer:
False.
Correct statement: The strategic metals such as titanium, chromium manganese, zirconium are used in the manufacturing of defence equipment.

Question $19 .$
Copper, silver and gold are called coinage metals.
Answer:
True.

Question $20 .$
For making ornaments, 24 - carat gold is used which is pure gold.
Answer:
False.
Correct statement: For making ornaments, 22 - carat gold is used which contains 22 parts of gold by weight and 2 parts of copper by weight.

Question 21.
The mineral from which a metal can be readily and economically extracted on a large scale is said to be ore.
Answer:
True.

Question $22 .$
The rocky impurity associated with the ore is called flux.
Answer:
False.
Correct statement: The rocky impurity associated with the ore is called gangue or matrix.

Question $23 .$
Slag is the fusible product formed when flux reacts with gangue during the extraction of metals.
Answer:
True,

Question 24.
Metals which have high chemical reactivity are found in a free state or in the native state.
Answer:
False.
Correct statement: Metals which have low chemical reactivity are found in a free state or in the native state.

Question $25 .$
Aluminium is the metal found most abundantly in the earth's crust.
Answer:
True

Question $26 .$
Aluminium is a reddish-brown metal and it is a bad conductor of heat and electricity.
Answer:
False.
Correct statement: Aluminium is a silvery - white metal and it is a good conductor of heat and electricity.

Question $27 .$
Aluminium reacts with strong caustic alkalis forming aluminates.
Answer:
True

Question 28.
Conc. Nitric acid renders aluminium active due to the formation of nitride film on its surface.
Answer:
False.
Correct statement: Cone. Nitric acid renders aluminium passive due to the formation of oxide film on its surface.

Question $29 .$
Aluminium is a powerful reducing agent.
Answer:
True.

Question 30 .
Duralumin alloy is light, having high tensile strength and corrosion-resistant.
Answer:
True.

Question 31 .
$\mathrm{Fe}$ and $\mathrm{Al}_{2} \mathrm{O}_{3}$ are used in thermite welding.
Answer:
False.
Correct statement: $\mathrm{Al}$ powder and $\mathrm{Fe}_{2} \mathrm{O}_{3}$ is used in thermite welding.

Question $32 .$
The chief ore of copper is Ruby copper.
Answer:
False.
Correct statement: The chief ore of copper is copper pyrite.

Question $33 .$
Iron is a lustrous greyish white metal and can be magnetised.
Answer:
True.

Question $34 .$
The rust has the chemical formula as $\mathrm{Fe}_{3} \mathrm{O}_{4}$.
Answer:
False.
Correct statement: The rust has the chemical formula as $\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{xH}_{2} \mathrm{O}$.

V. Assertion and Reason.
Question $1 .$
Assertion (A): Nobel gas is unreactive.
Reason $(R)$ : They have unstable electronic configuration in their valence shells.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are not correct
(c) (A) is correct but (R) is wrong
(d) $(A)$ is wrong but (R) is correct.
Answer:
(c) $(A)$ is correct but (R) is wrong

Question $2 .$
Assertion (A): The nature of bond in NaI molecule is covalent.
Reason (R): The electronegativity difference between $\mathrm{Na}$ and $I$ is $1.5$
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are not correct
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct

Question 3 .
Assertion (A): Haematite ore was purified by Hydraulic method.
Reason (R): Haematite is oxide ore.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are wrong
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct

Question 4 .
Assertion (A): Corundum is a chief ore of aluminium.
Reason (R): Molecular formula of Corundum is $\mathrm{Al}_{2} \mathrm{O}_{3}$
(a) (A) and (R) are correct, (R) explains the (A)
(b) (A) is correct, (R) is wrong
(c) (A) is wrong, (R) is correct
(d) (A) and (R) are correct, (R) doesn't explain (A).
Answer:
(c) (A) is wrong, (R) is correct

Question $5 .$
Assertion (A): The chemical properties of the elements in the same period are not similar.
Reason (R): As the electronic configuration changes across the period, the chemical properties of the elements are not similar.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are not correct
(c) (A) is correct but (R) is wrong
(d) $(A)$ is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct

Question $6 .$
Assertion (A): Copper, Silver and Gold are used in making coins and jewellery. So they are called coinage metals.
Reason (R): These metals release an enormous amount of nuclear energy.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are wrong

(c) (A) is correct but (R) is wrong
(d) $(A)$ is wrong but $(R)$ is correct.
Answer:
(c) (A) is correct but (R) is wrong

Question $7 .$
Assertion (A): Metals like Titanium, Chromium, Manganese and Zirconium are called strategic metals!
Reason (R): They find their applications in the manufacturing of defence equipment.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are wrong
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct

Question 8.
Assertion (A): Gold, Silver and Platinum are the metals that are found in a free state.
Reason (R): Those metals have low chemical reactivity and are found in a free state or in the native state.
(a) Both (A) and (R) are wrong
(b) Both (A) and (R) are correct
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct.
Answer:
(b) Both (A) and (R) are correct

Question $9 .$
Assertion (A): Aluminium occurs in the combined state.
Reason $(R)$ : It is a reactive metal and so it occurs in combined state.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are wrong
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct.
Answer:
(a) Both (A) and (R) are correct

Question $10 .$
Assertion (A): In the aluminothermic process, Iron oxide is reduced to iron by igniting with Aluminium powder.
Reason $(R)$ : Aluminium is a powerful reducing agent.
(a) Both (A) and (R) are wrong
(b) $(A)$ is correct but $(R)$ is wrong
(c) (A) is wrong but (R) is correct
(d) Both (A) and (R) are correct.
Answer:
(d) Both (A) and (R) are correct

Question $11 .$
Assertion (A): When iron is dipped in conc. $\mathrm{HNO}_{3}$ it becomes chemically inert (or) passive.
Reason $(R)$ : Iron becomes passive when treated with nitric acid is due to the formation of a layer of iron oxide $\mathrm{Fe}_{3} \mathrm{O}_{4}$ on its surface.
(a) Both (A) and (R) are correct
(b) $(A)$ is correct but $(R)$ is wrong
(c) (A) is wrong but (R) is correct
(d) Both (A) and (R) are wrong.
Answer:
(d) Both (A) and (R) are wrong

Question 12 .
Assertion (A): Duralumin is used in making aircraft, tools and pressure cookers.
Reason (R): Duralumin is an alloy that is light, strong, resistant to corrosion.
(a) Both (A) and (R) are wrong
(b) Both (A) and (R) are correct
(c) (A) is correct but (R) is wrong
(d) $(A)$ is wrong but (R) is correct.
Answer:
(b) Both (A) and (R) are correct

Question $13 .$
Assertion (A): Nickel steel is used in making cables, aircraft parts and propeller.
Reason $(R)$ : Nickel steel alloy is hard, brittle and polishable.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are wrong
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct.
Answer:
(c) (A) is correct but (R) is wrong

Question $14 .$
Assertion (A): Magnesium is used in a sacrificial protection method to prevent corrosion.
Reason $(R)$ : Magnesium is more reactive than iron. When it is coated on the articles made of steel, it sacrifices itself to protect steel.
(a) Both (A) and (R) are correct
(b) Both (A) and (R) are wrong
(c) (A) is correct but (R) is wrong
(d) (A) is wrong but (R) is correct.

Answer:
(a) Both (A) and (R) are correct

Question $15 .$
Assertion (A): Electroplating method not only protects but also enhances the metallic appearance.
Reason $(R)$ : Electroplating is a method of coating one metal with another by passing current.
(a) (A) is right, (R) is wrong
(b) $(A)$ is right, (R) is not relevant
(c) (A) is right, (R) is relevant
(d) Both $(A)$ and (R) are wrong.
Answer:
(c) (A) is right, (R) is relevant

VI. Short Answer Questions.
Question $1 .$
State modern periodic law.
Answer:
Modem periodic law states that the physical and chemical properties of elements are the periodic function of their atomic numbers.

Question $2 .$
Write the flow chart of the long form of the periodic table.
Answer:

Question $3 .$
The distance between the adjacent copper atoms in solid copper is $2.56 \AA$. Calculate what is the metallic radius of $\mathrm{Cu}$ ?
Answer:
Metallic radius of copper $=\frac{2.56}{2}=1.28 \AA$

Question $4 .$
Briefly write any four characteristics of a group in the periodic table.
Answer:
- The elements present in a group have the same valency.
- The elements present in a group have identical chemical properties.
- The physical properties of the elements in the group very gradually.
- The atomic radii of die elements present in a group increase downwards.

Question $5 .$
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 ( $\mathrm{ZnS})$.

Question 6.
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 $\mathrm{Al}_{2} \mathrm{O}_{3} \cdot 2 \mathrm{SiO}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ is the mineral of Aluminium.

Question 7.
Write the increasing order of radii of the following species.
(a) $\mathrm{Na}_{2} \mathrm{Na}^{+}, \mathrm{Cl}_{,} \mathrm{Cl}^{-}$
(b) $\mathrm{Li}, \mathrm{Na}, \mathrm{K}, \mathrm{Rb}$
Answer:
(a) $\mathrm{Na}^{+}, \mathrm{Cl}_{1}, \mathrm{Na}_{,} \mathrm{Cl}^{-}$
(b) $\mathrm{Li}, \mathrm{Na}, \mathrm{K}, \mathrm{Rb}$

Question 8.
Differentiate ore and mineral.
Answer:

Question $9 .$
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.

Question $10 .$
Elements $a, b, c$ and $\mathrm{d}$ have the following electronic configurations
(a) $1 s^{2} 2 s^{2} 2 p^{6}$
(b) $I s^{2}, 2 s^{2}, 2 p^{6}, 3 s^{2}, 3 p^{1}$
(c) $\mathrm{Is}^{2}, 2 \mathrm{~s}^{2}, 2 \mathrm{p}^{6}, 3 \mathrm{~s}^{2}, 3 \mathrm{p}^{6}$
(d) $\mathrm{Is}^{2}, 2 \mathrm{~s}^{2}, \mathrm{Ip}^{1}$
Answer:
(a) and (c), (b) and (d). Because the number of valence electrons are the same.

Question $11 .$
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 $\rightarrow$ slag
$\mathrm{CaO}+\mathrm{SiO}_{2} \rightarrow \mathrm{CaSiO}_{3}$

Question $12 .$
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.

Question $13 .$
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.

Question $14 .$
How does Aluminium reacts with air?
Answer:

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

Question $15 .$
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 $\mathrm{H}_{2}$ gas.

Question $16 .$
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.

Question $17 .$
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.
$\mathrm{Fe}_{2} \mathrm{O}_{3}+2 \mathrm{Al} \rightarrow 2 \mathrm{Fe}+\mathrm{Al}_{2} \mathrm{O}_{3}+$ heat

Question $18 .$
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 $\mathrm{CuO}, \mathrm{Cu}_{2} \mathrm{O}$.

Question $19 .$
Explain the action of dilute nitric acid with copper.
Answer:
Copper reacts with dil. $\mathrm{HNO}_{3}$ with the liberation of Nitric oxide gas.

Question $20 .$
What happens when copper is treated with conc. $\mathrm{HNO}_{3}$ and with conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$ ?
Answer:

Question $21 .$
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.

Question $22 .$
Explain the action of air with iron.
Answer:
$3 \mathrm{Fe}+2 \mathrm{O}_{2} \rightarrow \mathrm{Fe}_{3} \mathrm{O}_{4}[\mathrm{Magnetic}$ oxide (Black)]

Question 23.
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.

Question $24 .$
Explain the action of steam with iron.

Answer:

Question $25 .$
Mention the types of iron on the basis of carbon content.
Answer:

Question $26 .$
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 $\mathrm{O}_{2}, \mathrm{~N}_{2}, \mathrm{SO}_{2}, \mathrm{H}_{2} \mathrm{~S}$ etc... It occurs at high temperature, of all the gases mentioned above $\mathrm{O}_{2}$ is the most reactive gas to impart the chemical attack.

Question $27 .$
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.

Question $28 .$
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.

Question $29 .$
Define corrosion.
Answer:
Corrosion is defined as the slow and steady destruction of a metal by the environment. It results in the deterioration of the metal to form metal compounds by means of chemical reactions with the environment.

Question $30 .$
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 $\mathrm{CO}_{2}$ and moisture.
$$
2 \mathrm{Cu}+\mathrm{O}_{2}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{CUCO}_{3} \cdot \mathrm{CU}(\mathrm{OH})_{2}
$$

Question $31 .$
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.

Question $32 .$
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.

Question $33 .$
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.

Question $34 .$
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.

Question $35 .$
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.

Question $36 .$
Write the action of dil.HCl and dil. $\mathrm{H}_{2} \mathrm{SO}_{4}$ with iron.
Answer:
(i) $\mathrm{Fe}+2 \mathrm{HCl} \rightarrow \mathrm{FeCl}_{2}+\mathrm{H}_{2} \uparrow$
(ii) $\mathrm{Fe}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{FeSO}_{4}+\mathrm{H}_{2} \uparrow$

Question $37 .$
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.

Question $38 .$
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.

Question $39 .$
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.

Question 40 .
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.

Question $41 .$
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.

Question $42 .$
Give a single term for each of the following:
(i) The process of extracting the ores from the Earth's crust is called:
Answer:
Mining
(ii) The rocky impurities associated with an ore is called:
Answer:
Gangue or matrix
(iii) The substance added to the ore to reduce fusion temperature:
Answer:
Flux
(iv) Noble metals occur in this state:
Answer:
Native

Question $43 .$
How will you convert copper into copper carbonate?
Answer:
Copper reacts with oxygen in the presence of $\mathrm{CO}_{2}$ and moisture to give copper carbonate.
$2 \mathrm{Cu}+\mathrm{O}_{2}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{CuCO}_{3} . \mathrm{Cu}(\mathrm{OH})_{2}$ (Copper Carbonate).

Question $44 .$
Mention the uses of iron.
Answer:
Uses of iron:
1. Pig iron (Iron with $2-4.5 \%$ of carbon): It is used in making pipes, stoves, radiators, railings, manhole covers and drain pipes.
2. 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.
3. Wrought iron (Iron with $0.25-2 \%$ of wrought carbon): It is used in making springs, anchors and electromagnets.

Question $45 .$
What are the chemical properties of metals in terms of
1. valence electrons
2. Atomicity.
Answer:
1. Valence electrons: Metals usually have 1,2 or 3 electrons in their outermost shell.
2. Atomicity: Metals are usually monoatomic in their vapour state.

Question $46 .$
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).

Question $47 .$
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 $\mathrm{O}_{2}, \mathrm{~N}_{2}$, $\mathrm{SO}_{2}, \mathrm{H}_{2} \mathrm{~S}$ etc. in which $\mathrm{O}_{2}$ is more reactive.
- It occurs at high temperature

Question $48 .$
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.

Question $49 .$
What is electroplating?
Answer:
Electroplating is a method of coating one metal over another metal by passing an electric current.

VII. Long Answer Questions.
Question $1 .$
Explain the variation of ionisation energy along the group and period.
Answer:
- As the atomic size decreases from left to right in a period, more energy is required to remove the electrons. So, the ionisation energy increases throughout the period.
- Down the group, the atomic size increases and hence the valence electrons are loosely bound. They require relatively less energy for the removal. Thus, ionisation energy decreases down the group in the periodic table.

Question 2.
Explain the electrolytic refining of copper.
Answer:
(i) Blister copper contains $98 \%$ of pure Cu and $2 \%$ of impurities and is purified by electrolytic refining.
For electrolytic refining of $\mathrm{Cu}$ we use:
Cathode: A thin plate of pure $\mathrm{Cu}$.
Anode: A block of impure $\mathrm{Cu}$
Electrolyte: $\mathrm{CuSO}_{4}+$ dil $_{2} \mathrm{SO}_{4}$
(ii) When electric current is passed through the electrolytic solution, Pure Cu gets deposited at the cathode and the impurities settle at the bottom of the anode in the form of anode mud.

Question $3 .$
Explain Gravity separation method.
Answer:
Gravity Separation (or) Hydraulic method:
1. Principle: The difference in the densities or specific gravities of the ore and the gangue is the main principle behind this method. Oxide ores are purified by this method,
e.g., Haematite $\mathrm{Fe}_{2} \mathrm{O}_{3}$ the ore of iron.
2. Method: The ore is poured over a sloping, vibrating corrugated table with grooves and a jet of water is allowed to flow over it. The denser ore particles settle down in the grooves and lighter gangue particles are washed down by the water.

Question $4 .$
Discuss the magnetic separation methods.
Answer:
Magnetic separation method:
Principle: The magnetic properties of the ores from the basis of separation. When either the ore or the gangue is magnetic, this method is employed, e.g., Tinstone $\mathrm{SnO}_{2}$, the ore of $\operatorname{tin}$.

Method: The crushed ore is placed over a conveyer belt which rotates around two metal wheels, one of which is magnetic. The magnetic particles are attracted to the magnetic wheel and fall separately apart from the nonmagnetic particles.

Question $5 .$
Explain the froth floatation process.
Answer:
Froth floatation Process:
Principle: 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, e.g., Zinc blende (ZnS).

Method: The crushed ore is taken in a large tank containing oil and water and agitated with a current of compressed air. The ore is wetted by the oil and gets separated from the gangue in the form of froth. Since the ore is lighter, it comes on the surface with the froth and the impurities are left behind, e.g., Zinc blende ( $\mathrm{ZnS})$.

Question $6 .$
How will you extract aluminium from its ore?
Answer:
The extraction of aluminium from bauxite involves two steps:
(i) Conversion of bauxite into alumina - Baeyer's Process
The conversion of Bauxite into Alumina involves the following steps:
Bauxite ore is finely ground and heated under pressure with a solution of concentrated caustic soda solution at $150^{\circ} \mathrm{C}$ to obtain sodium metal aluminate.
On diluting sodium meta aluminate with water, a precipitate of aluminium hydroxide is formed. The precipitate is filtered, washed, dried and ignited at $1000^{\circ} \mathrm{C}$ to get alumina.
$$
2 \mathrm{Al}(\mathrm{OH})_{3} \stackrel{100 \mathrm{C}}{\longrightarrow} \mathrm{Al}_{2} \mathrm{O}_{3}+3 \mathrm{H}_{2} \mathrm{O}
$$
(ii) Electrolytic reduction of alumina - Hall's Process
Aluminium is produced by the electrolytic reduction of fused alumina $\left(\mathrm{Al}_{2} \mathrm{O}_{3}\right)$ in the electrolytic cell.

Cathode: Iron tank linked with graphite
Anode: A bunch of graphite rods suspended in a molten electrolyte.
Electrolyte: Pure alumina + molten cryolite + fluorspar (fluorspar lowers the fusion temperature of electrolyte)
Temperature: $900-950^{\circ} \mathrm{C}$
The voltage used: $5-6 \mathrm{~V}$
Aluminium is deposited at the cathode and oxygen gas is liberated at the anode. Oxygen combines with graphite to form $\mathrm{CO}_{2}$.

Question $7 .$
Explain the extraction of copper from copper pyrites.
Answer:
Extraction of copper from copper pyrites involves the following steps:
(i) The concentration of ore: The ore is crushed and then concentrated by froth floatation process.
(ii) Roasting: The concentrated ore is roasted in excess of air. During the process of roasting, the moisture and volatile impurities are removed. Sulphur, phosphorus, arsenic and antimony are
removed as oxides. Copper pyrite is partly converted into sulphides of copper and iron. $2 \mathrm{CuFeS}_{2}+\mathrm{O}_{2} \rightarrow \mathrm{Cu}_{2} \mathrm{~S}+2 \mathrm{FeS}+\mathrm{SO}_{2} \uparrow$
(iii) Smelting: The roasted ore is mixed with powdered coke and sand and is heated in a blast furnace to obtain matte $\left(\mathrm{Cu}_{2} \mathrm{~S}+\mathrm{FeS}\right)$ and slag. The slag is removed as waste.
(iv) Bessemerisation: The molten matte is transferred to the Bessemer converter in order to obtain blister copper. Ferrous sulphide from matte is oxidized to ferrous oxide, which is removed as slag using silica.

(v) Refining: Blister copper contains $98 \%$ of pure copper and $2 \%$ of impurities and is purified A by electrolytic refining. This method is used to get metal of a high degree of purity. For electrolytic refining of copper, we use:
Cathode: A thin plate of pure copper metal.
Anode: A block of impure copper metal.
Electrolyte: Copper sulphate solution acidified with sulphuric acid.
When an electric current is passed through the electrolytic solution, pure copper gets deposited at the cathode and the impurities settle at the bottom of the anode in the form of sludge called anode mud.

Question 8.
Explain the metallurgy of iron.
Answer:
Iron is chiefly extracted from haematite ore $\left(\mathrm{Fe}_{2} \mathrm{O}_{3}\right)$ :
(i) Concentration by Gravity Separation: The powdered ore is washed with steam of water. As a result, the lighter sand particles and other impurities are washed away and the heavier ore particles settle down.
(ii) Roasting and Calcination: The concentrated ore is strongly heated in a limited supply of air in a reverberatory furnace. As a result, moisture is driven out and sulphur, arsenic and phosphorus impurities are oxidized off.
(iii) Smelting (in a Blast Furnace): 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. There are three important regions in the furnace.

a. The Lower Region (Combustion Zone):
The temperature is at $1500^{\circ} \mathrm{C}$. In this region, coke bums with oxygen to form $\mathrm{CO}_{2}$ when the charge comes in contact with a hot blast of air.

It is an exothermic reaction since heat is liberated.
b. The Middle Region (Fusion Zone):
The temperature prevails at $1000^{\circ} \mathrm{C}$. In this region, $\mathrm{CO}_{2}$ is reduced to $\mathrm{CO}$.

Limestone decomposes to calcium oxide and $\mathrm{CO}_{2}$

These two reactions are endothermic due to absorption of heat. Calcium oxide combines with silica to form calcium silicate slag.
$$
\mathrm{CaO}+\mathrm{SiO}_{2} \rightarrow \mathrm{CaSiO}_{3}
$$
c. The Upper Region (Reduction Zone): The temperature prevails at $400^{\circ} \mathrm{C}$. In this region carbon monoxide reduces ferric oxide to form a fairly pure spongy iron.
$$
\mathrm{Fe}_{2} \mathrm{O}_{3}+3 \mathrm{CO} \stackrel{400^{\circ} \mathrm{C}}{\longrightarrow} 2 \mathrm{Fe}+3 \mathrm{CO}_{2}
$$
The molten iron is collected at the bottom of the furnace after removing the slag.
The iron thus formed is called pig iron. It is remelted and cast into different moulds. This iron is called cast iron.

Question $9 .$
Explain the types of alloys.
Answer:
Based on the presence or absence of Iron, alloys can be classified into:
1. Ferrous alloys: Contain Iron as a major component.
A few examples of ferrous alloys are Stainless Steel, Nickel Steel etc.
2. Non - ferrous alloys: These alloys do not contain Iron as a major component.
For example, Aluminium alloy, Copper alloy etc.
Copper Alloys (Non - ferrous):

VIII. HOT Questions.
Question $1 .$
What would be the atomic number of the next
1. alkali metal
2. alkaline earth metal
3. Halogens
4. inert gas, if discovered in future.
Answer:
1. Alkali metal: $118+1=119$
2. Alkaline earth metal: 120
3. Halogens: 117
4. Inert gas: 118

Question $2 .$
Explain the mechanism of rusting?
Answer:
Rust is chemically known as hydrated ferric oxide (it is formulated as $\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{xH}_{2} \mathrm{O}$ ).
Rusting results in the formation of scaling reddish - brown hydrated ferric oxide on the surface of iron and iron-containing materials.

Question 3 .
All ores are minerals, but ait minerals are not ores. Why?
Answer:
- The elements or compounds of the metals which occur in nature in the earth's crust are called minerals whereas ore is a mineral from which the metal is profitably extracted.
- For example, aluminium exists in the two mineral forms, that is clay and bauxite. But aluminium is mainly extracted from bauxite which contains $70 \%$ aluminium oxide. So, bauxite is an ore of aluminium whereas clay is not ore.
- So, all ores are minerals but all minerals need not be ores.

Question $4 .$
Why the graphite rods acting as anode in the Hall's process should be replaced periodically?
Answer:
During Hall's Process, the carbon electrodes get consumed, so they have to be replaced periodically.

Question $5 .$
Anionic radius Is higher than the corresponding neutral atom. Give reason.
Answer:
When an atom gains one or more electrons it forms an anion. During the formation of anion, the number of orbital electrons becomes greater than the nuclear charge. Hence, the electrons are not strongly attracted by the lesser number of nuclear charges. Hence anionic radius is higher than the corresponding neutral atom.

Question $6 .$
A reddish - brown metal $A$, when exposed to moist air, forms a green layer $B$. When $A$ is heated at different temperatures in the presence of $\mathrm{O}_{2}$, it forms two types of oxides - $\mathrm{C}$ (black) and D (red).
Identify $\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$ and write the balanced equation.
Answer:
(i) A reddish - brown metal $\mathrm{A}$ is a copper (Cu).

(iii) When copper is heated at different temperature in the presence of oxygen, it forms two types of oxides $\mathrm{CuO}$ and $\mathrm{Cu}_{2} \mathrm{O}$. (C and D)

(iii) When copper is heated at different temperature in the presence of oxygen, it forms two types of oxides $\mathrm{CuO}$ and $\mathrm{Cu}_{2} \mathrm{O} .(\mathrm{C}$ and $\mathrm{D})$

Question $7 .$
$\mathrm{A}$ silvery - white metal on treatment with $\mathrm{NaOH}$ and $\mathrm{HCl}$ liberates $\mathrm{H}_{2}$ gas to form $\mathrm{B}$ and $\mathrm{C}$ respectively. The metal A will not react with acid D due to the formation of a passive film on the surface. Hence it is used for transporting acid D. Identify A, B, C, D and support your answer with balanced equations.
Answer:
(i) A silvery - white metal (A) is Aluminium (Al).
(ii) Aluminium reacts with $\mathrm{NaOH}$ to form $\mathrm{B}$ which is known as sodium meta aluminate with the liberation of $\mathrm{H}_{2}$ gas.

(iv) Aluminium does not react with conc. nitric acid $\left(\mathrm{HNO}_{3}\right)$ which is known as $\mathrm{D}$, due to the formation of a passive film on the surface.

Question $8 .$
Metal A belongs to period 4 and group 8. A in red hot condition reacts with steam to form $B$. A reacts with dilute $\mathrm{HNO}_{3}$ to give $\mathrm{C}$. $\mathrm{A}$ again reacts with conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$ to give $\mathrm{D}$. Find $\mathrm{A}, \mathrm{B}, \mathrm{C}$ and $\mathrm{D}$ with suitable reaction.
Answer:
(i) Metal (A) belongs to period 4 and group 8 is iron (Fe).
(ii) Iron (A) reacts with steam to form magnetic oxide (B)