Select the wrong statement.

Options

A. The electrolysis of molten `CaH_(2)` liberates `H_(2)` at cathode
B. During the discharge of lead storage battery, sulphuric acid is consumed.
C. Sulphur acts as a polymerizing agent in the vulcanization of rubber.
D. Galvanization of iron denotes coating with `Zn`.

Explanation

To solve the question of selecting the wrong statement, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** Electrolysis of molten calcium hydride liberates hydrogen at the cathode.

- Calcium hydride (CaH₂) dissociates into calcium ions (Ca²⁺) and hydride ions (H⁻) during electrolysis.
- At the cathode, reduction occurs. The possible reduction reactions are:
- Ca²⁺ + 2e⁻ → Ca (s)
- H⁻ + e⁻ → H₂ (g)
- However, H⁻ cannot be reduced to H₂ because it is already in a reduced state. Instead, H⁻ will be oxidized at the anode to produce hydrogen gas (H₂).
- Therefore, the statement is incorrect as it claims hydrogen is liberated at the cathode.

**Conclusion for Step 1:** The first statement is wrong.

### Step 2: Analyze the second statement
**Statement:** During the discharge of a lead storage battery, sulfuric acid is consumed.

- In a lead storage battery, the discharge reaction involves the conversion of lead dioxide (PbO₂) and sponge lead (Pb) into lead sulfate (PbSO₄) while consuming sulfuric acid (H₂SO₄).
- Therefore, this statement is correct.

**Conclusion for Step 2:** The second statement is correct.

### Step 3: Analyze the third statement
**Statement:** Sulfur acts as a polymerization agent for the vulcanization of rubber.

- Vulcanization is a process that involves the addition of sulfur to rubber, which creates cross-links between the polymer chains, enhancing the elasticity and strength of rubber.
- Thus, this statement is also correct.

**Conclusion for Step 3:** The third statement is correct.

### Step 4: Analyze the fourth statement
**Statement:** Galvanization of iron denotes coating with zinc.

- Galvanization is indeed the process of applying a protective zinc coating to iron or steel to prevent rusting.
- This statement is correct.

**Conclusion for Step 4:** The fourth statement is correct.

### Final Conclusion
After analyzing all the statements, we find that the first statement is the only incorrect one. Therefore, the answer to the question is:

**Answer:** The wrong statement is option A: "Electrolysis of molten calcium hydride liberates hydrogen at the cathode."

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