Which of the following statement is/are correct?

Options

A. Aluminium carbide as well as beryllium carbide produce methane gas on treatment with water
B. On reacting with water, calcium carbide `(CaC_(2))` produces acetylene while magnesium carbide `(Mg_(2)C_(3))` gives propyne
C. Calcium carbide has one sigma and two pi bonds
D. Diamond is more stable than graphite.

Answer

To determine which of the statements are correct, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** Aluminum carbide (Al4C3) and beryllium carbide (Be2C) produce methane gas (CH4) when treated with water.

**Reaction for Aluminum Carbide:**
\[ \text{Al}_4\text{C}_3 + 12 \text{H}_2\text{O} \rightarrow 4 \text{Al(OH)}_3 + 3 \text{CH}_4 \]

**Reaction for Beryllium Carbide:**
\[ \text{Be}_2\text{C} + 4 \text{H}_2\text{O} \rightarrow 2 \text{Be(OH)}_2 + \text{CH}_4 \]

Both reactions produce methane gas. Therefore, the first statement is **correct**.

### Step 2: Analyze the second statement
**Statement:** On reacting with water, calcium carbide (CaC2) produces acetylene (C2H2), while magnesium carbide (Mg2C3) gives propene (C3H6).

**Reaction for Calcium Carbide:**
\[ \text{CaC}_2 + 2 \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2 + \text{C}_2\text{H}_2 \]

This reaction produces acetylene, which is correct.

**Reaction for Magnesium Carbide:**
\[ \text{Mg}_2\text{C}_3 + 6 \text{H}_2\text{O} \rightarrow 2 \text{Mg(OH)}_2 + \text{C}_3\text{H}_6 \]

This reaction produces propene, which is also correct. Therefore, the second statement is **correct**.

### Step 3: Analyze the third statement
**Statement:** Calcium carbide has one sigma and two pi bonds.

The structure of calcium carbide (CaC2) can be represented as:
\[ \text{Ca} \equiv \text{C} - \text{C} \equiv \text{Ca} \]

In this structure, there is one sigma bond between the carbon atoms and two pi bonds. Therefore, the third statement is **correct**.

### Step 4: Analyze the fourth statement
**Statement:** Diamond is more stable than graphite.

This statement is incorrect. While diamond has a rigid structure and is kinetically stable, graphite is thermodynamically more stable due to its lower energy state. Therefore, the fourth statement is **incorrect**.

### Conclusion
The correct statements are:
- Statement 1: Correct
- Statement 2: Correct
- Statement 3: Correct
- Statement 4: Incorrect

Thus, the correct answer is **A, B, and C**.

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