Metal carbides on reaction with `H_2O` form `CH_4` , Carbide can be

Options

A. `CaC_2`
B. `Mg_3C_2`
C. `Be_2C`
D. All of these

Answer

To solve the question regarding which metal carbide reacts with water to form methane (CH₄), we can follow these steps:

### Step 1: Identify the Metal Carbides
We need to identify the metal carbides that are known to react with water to produce methane. The options provided typically include carbides of alkaline earth metals or transition metals.

### Step 2: Write the Reaction
The general reaction of a metal carbide (MC) with water (H₂O) can be represented as:
\[ \text{MC} + \text{H}_2\text{O} \rightarrow \text{M(OH)}_2 + \text{CH}_4 \]
Where M represents the metal.

### Step 3: Analyze the Given Options
Let's analyze the provided options for metal carbides:
1. **CaC₂ (Calcium Carbide)**
2. **Mg₃C₂ (Magnesium Carbide)**
3. **Be₂C (Beryllium Carbide)**
4. **Others (if any)**

### Step 4: Determine the Reaction Products
- **For CaC₂**:
\[ \text{CaC}_2 + 2\text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{C}_2\text{H}_2 \]
(produces acetylene, not methane)

- **For Mg₃C₂**:
\[ \text{Mg}_3\text{C}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Mg(OH)}_2 + \text{C}_2\text{H}_6 \]
(produces ethane, not methane)

- **For Be₂C**:
\[ \text{Be}_2\text{C} + 4\text{H}_2\text{O} \rightarrow 2\text{Be(OH)}_2 + \text{CH}_4 \]
(produces methane)

### Step 5: Conclusion
From the analysis, only **Be₂C** reacts with water to produce methane (CH₄). Therefore, the correct answer is **Be₂C**.

### Final Answer:
The carbide that can produce CH₄ when reacted with water is **Be₂C**.

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