An element A (atomic weight = 12) and B (atomic weight = 35.5) combines to form a compound X. If 4 mol of B combines with 1 mol of A to give 1 mol of X. The weight of 1 mol of X would be :

Options

A. 47.5 g
B. 74.0 g
C. 154.0 g
D. 148.8 g

Explanation

To find the weight of 1 mole of compound X formed by elements A and B, we can follow these steps:

### Step 1: Identify the atomic weights
- The atomic weight of element A = 12 g/mol
- The atomic weight of element B = 35.5 g/mol

### Step 2: Determine the moles of A and B used
- According to the problem, 1 mole of A combines with 4 moles of B to form 1 mole of compound X.

### Step 3: Calculate the total mass of A and B
- Mass of A = Atomic weight of A × Moles of A
\[ \text{Mass of A} = 12 \, \text{g/mol} \times 1 \, \text{mol} = 12 \, \text{g} \]

- Mass of B = Atomic weight of B × Moles of B
\[ \text{Mass of B} = 35.5 \, \text{g/mol} \times 4 \, \text{mol} = 142 \, \text{g} \]

### Step 4: Calculate the total mass of compound X
- The total mass of compound X is the sum of the masses of A and B:
\[ \text{Mass of X} = \text{Mass of A} + \text{Mass of B} = 12 \, \text{g} + 142 \, \text{g} = 154 \, \text{g} \]

### Step 5: Conclusion
- Therefore, the weight of 1 mole of compound X is 154 g.

### Final Answer
The weight of 1 mole of compound X is **154 g**.

---