When 1 mole of a substance `(X)` was treated with an excess of water, 2 moles of readily combustible gas were produced along with solution which when reacted with `CO_(2)` gas produced a white turbidity. The substance `(X)` could be

Options

A. Ca
B. `CaH_(2)`
C. `Ca(OH)_(2)`
D. `Ca(NO_(3))_(2)`

Explanation

To solve the question, we need to analyze the information given about the substance \(X\) when treated with water and its subsequent reactions.

### Step-by-Step Solution:

1. **Understanding the Reaction with Water:**
- We know that when 1 mole of substance \(X\) is treated with excess water, it produces 2 moles of a readily combustible gas. The most common combustible gas produced in reactions with water is hydrogen gas (\(H_2\)).
- Therefore, we are looking for a substance that can produce 2 moles of \(H_2\) when reacted with water.

2. **Identifying Possible Substances:**
- Let's consider some possible candidates for substance \(X\):
- **Calcium (Ca):** When treated with water, it produces calcium hydroxide and hydrogen gas, but only 1 mole of \(H_2\) is produced.
- **Calcium Hydroxide (Ca(OH)₂):** This does not produce any gas when treated with water.
- **Calcium Nitrate (Ca(NO₃)₂):** This does not produce gas when treated with water.
- **Calcium Hydride (CaH₂):** When treated with water, it reacts to form calcium hydroxide and produces 2 moles of \(H_2\):
\[ \text{CaH}_2 + 2 \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + 2 \text{H}_2 \]

3. **Formation of White Turbidity:**
- The solution formed after the reaction with water is calcium hydroxide. When calcium hydroxide reacts with carbon dioxide (\(CO_2\)), it forms calcium carbonate (\(CaCO_3\)), which is known to produce a white turbidity:
\[ \text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3 + \text{H}_2\text{O} \]
- Calcium carbonate precipitates out of the solution, resulting in a cloudy appearance (white turbidity).

4. **Conclusion:**
- Based on the above analysis, the substance \(X\) that meets all the criteria given in the question is **Calcium Hydride (CaH₂)**.

### Final Answer:
The substance \(X\) could be **Calcium Hydride (CaH₂)**.

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