The gas given off at cathode during the electrolysis of acidulated water is …………..

Options

A. Nitrogen
B. Hydrogen
C. Oxygen
D. None of these

Explanation

To determine the gas given off at the cathode during the electrolysis of acidulated water, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electrolysis**:
- Electrolysis is a process that uses electrical energy to drive a non-spontaneous chemical reaction. In this case, we are looking at the electrolysis of water that has been acidulated (mixed with a dilute acid).

2. **Purpose of Acidulation**:
- Pure water is a poor conductor of electricity. By adding a dilute acid (like sulfuric acid), we increase the conductivity of the water, allowing the electrolysis process to occur more efficiently.

3. **Dissociation of Water**:
- When acidulated water is subjected to electrolysis, it dissociates into ions:
- Water (H₂O) dissociates into hydrogen ions (H⁺) and hydroxide ions (OH⁻).

4. **Identifying the Cathode**:
- The cathode is the negatively charged electrode where reduction occurs. In electrolysis, cations (positively charged ions) migrate towards the cathode.

5. **Reduction at the Cathode**:
- At the cathode, the hydrogen ions (H⁺) will gain electrons (reduction) to form hydrogen gas (H₂):
- The half-reaction at the cathode can be represented as:
\[ 2H^+ + 2e^- \rightarrow H_2(g) \]
- This indicates that two hydrogen ions gain two electrons to produce one molecule of hydrogen gas.

6. **Conclusion**:
- Therefore, the gas given off at the cathode during the electrolysis of acidulated water is hydrogen gas (H₂).

### Final Answer:
The gas given off at the cathode during the electrolysis of acidulated water is **hydrogen gas (H₂)**.

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