The electrical expenditure is two rupees to produce one gram of calcium from fused `CaSO_4`. What is the production cost of 2 grams of hydrogen produced electrically from acidulated water?

Explanation

To solve the problem, we need to establish the relationship between the production of calcium from fused `CaSO4` and the production of hydrogen from acidulated water. Here's a step-by-step breakdown of the solution:

### Step 1: Understand the electrochemical reactions
- The electrochemical reaction for producing calcium from `CaSO4` is:
\[ \text{Ca}^{2+} + 2e^- \rightarrow \text{Ca} \]
- The electrochemical reaction for producing hydrogen from acidulated water is:
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