1. ⇒ (JEE Main 2023 (Online) 12th April Morning Shift )

For lead storage battery pick the correct statements

A. During charging of battery, ${PbSO}_{4}$ on anode is converted into ${PbO}_{2}$

B. During charging of battery, ${PbSO}_{4}$ on cathode is converted into ${PbO}_{2}$

C. Lead storage battery consists of grid of lead packed with ${PbO}_{2}$ as anode

D. Lead storage battery has $\sim 38 %$ solution of sulphuric acid as an electrolyte

Choose the correct answer from the options given below:

(A) A, B, D only

(B) B, C only

(C) B, C, D only

(D) B, D only

Explanation

Correct answer is D

Let's review each statement:

A. During charging of battery, PbSO₄ on anode is converted into PbO₂.

This statement is incorrect. During charging, PbSO₄ on the anode (lead plate) is converted to Pb, not PbO₂.

B. During charging of battery, PbSO₄ on cathode is converted into PbO₂.

This statement is correct. During charging, PbSO₄ on the cathode (lead dioxide plate) is converted back to PbO₂.

C. Lead storage battery consists of grid of lead packed with PbO₂ as anode.

This statement is incorrect. The anode in a lead-acid battery is made of lead (Pb), not lead dioxide (PbO₂). The cathode is made of lead dioxide (PbO₂).

D. Lead storage battery has ∼38% solution of sulphuric acid as an electrolyte.

This statement is correct. The electrolyte in a lead-acid battery is a solution of about 35-38% sulfuric acid (H₂SO₄) in water.

Therefore, the correct answer is:

B, D only.

2. ⇒ (JEE Main 2022 (Online) 28th July Morning Shift )

Match List - I with List - II.

	List - I		List - II
(A)	$C d (s) + 2 N i (O H)_{3} (s) \to C d O (s) + 2 N i (O H)_{2} (s) + H_{2} O (l)$	(I)	Primary battery
(B)	$Z n (H g) + H g O (s) \to Z n O (s) + H g (l)$	(II)	Discharging of secondary battery
(C)	$2 P b S O_{4} (s) + 2 H_{2} O (l) \to P b (s) + P b O_{2} (s) + 2 H_{2} S O_{4} (a q)$	(III)	Fuel cell
(D)	$2 H_{2} (g) + O_{2} (g) \to 2 H_{2} O (l)$	(IV)	Charging of secondary battery

Choose the correct answer from the options given below:

(A) $(A) - (I), (B) - (II), (C) - (III), (D) - (IV)$

(B) $(A) - (IV), (B) - (I), (C) - (II), (D) - (III)$

(C) $(A) - (II), (B) - (I), (C) - (IV), (D) - (III)$

(D) $(A) - (II), (B) - (I), (C) - (III), (D) - (IV)$

Explanation

Correct answer is C

(a) $Cd (s) + 2 Ni (OH)_{3} (s) \to CdO (s) + 2 Ni (OH)_{2} (s)$ $+ H_{2} O (l)$ Discharge of secondary Battery

(b) $Zn (Hg) + HgO$ (s) $\to ZnO (s) + Hg (l)$ (Primary Battery Mercury cell)

(c) $2 {PbSO}_{4} (s) + 2 H_{2} O (l) \to Pb (s) + {PbO}_{2} (s) +$ $2 H_{2} {SO}_{4} (aq)$ (Charging of secondary Battery)

(d) $2 H_{2} (g) + O_{2} (g) \to 2 H_{2} O (l)$ (Fuel cell)

3. ⇒ (JEE Main 2021 (Online) 26th February Morning Shift )

Compound A used as a strong oxidizing agent is amphoteric in nature. It is the part of lead storage batteries. Compound A is :

(A) PbO

(B) PbO₂

(C) PbSO₄

(D) Pb₃O₄

Explanation

Correct answer is B

PbO₂ is strong oxidizing agent because Pb⁺⁴ is not stable and can be easily reduced to Pb⁺².

PbO₂ is used in lead storage batteries. It is also amphoteric in nature.

4. ⇒ (JEE Main 2016 (Online) 10th April Morning Slot )

Identify the correct statement :

(A) Iron corrodes in oxygen-free water.

(B) Iron corrodes more rapidly in salt water because its electrochemical potential is higher.

(C) Corrosion of iron can be minimized by forming a contact with another metal with a higher reduction potential.

(D) Corrosion of iron can be minimized by forming an impermeable barrier at its surface.

Explanation

Correct answer is D

The two conditions necessary for the corrosion of iron to take place are presence of moisture and oxygen. Factors that catalyse the process of rusting are the presence of carbon dioxide, acids and impurities. It can be minimised by introducing of a barrier film between surface of iron and atmosphere. This can be done by

(i) painting the surface.

(ii) coating the surface with oil or grease.

(iii) electroplating iron with non-corrosive metals such as nickel or chromium.

(iv) covering the surface of iron with layer of more active metal with higher oxidation potential like zinc.

5. ⇒ (JEE Main 2016 (Online) 9th April Morning Slot )

What will occur if a block of copper metal is dropped into a beaker containing a solution of 1M ZnSO₄?

(A) The copper metal will dissolve and zinc metal will be deposited.

(B) The copper metal will dissolve with evolution of hydrogen gas.

(C) The copper metal will dissolve with evolution of oxygen gas.

(D) No reaction will occur.

Explanation

Correct answer is D

In the reaction of copper with zinc ions, zinc is more active (easily oxidised) than copper; thus, no reaction will take place.

6. ⇒ (JEE Main 2016 (Offline) )

Galvanization is applying a coating of :

(A) Cr

(B) Cu

(C) Zn

(D) Pb

Explanation

Correct answer is C

Galvanization is the process by which zinc is coated over corrosive (easily rusted) metals to prevent them from corrosion.

7. ⇒ (AIEEE 2004)

In a hydrogen – oxygen fuel cell, combustion of hydrogen occurs to :

A. generate heat

B. remove adsorbed oxygen from electrode surfaces

C. produce high purity water

D. create potential difference between the two electrodes

Correct Answer is Option (D)

In $H_{2} - O_{2}$ fuel cell, the combustion of $H_{2}$ occurs to create potential difference between the two electrodes

8. ⇒ (AIEEE 2003)

Several blocks of magnesium are fixed to the bottom of a ship to :

A. make the ship lighter

B. prevent action of water and salt

C. prevent puncturing by under-sea rocks

D. keep away the sharks

Correct Answer is Option (B)

Magnesium provides cathodic protection and prevent rusting or corrosion.

⇒Electrochemistry

Topic 4 : Commercial Cells amd Corrosion