One litre of a gas at STP weight 1.16 g it can possible be

Options

A. `C_(2)H_(2)`
B. CO
C. `O_(2)`
D. `NH_(3)`

Answer

To solve the problem of determining which gas has a molar mass corresponding to the weight of 1.16 g for 1 liter at STP, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Conditions**: At Standard Temperature and Pressure (STP), 1 mole of any ideal gas occupies 22.4 liters.

2. **Calculate the Number of Moles**:
- Given that the volume of the gas is 1 liter, we can calculate the number of moles (n) using the formula:
\[ n = \frac{\text{Volume}}{22.4 \text{ L/mol}} = \frac{1 \text{ L}}{22.4 \text{ L/mol}} \approx 0.04464 \text{ moles} \]

3. **Use the Mass to Find Molar Mass**:
- We know the mass of the gas is 1.16 g. The relationship between mass, number of moles, and molar mass (M) is given by:
\[ n = \frac{\text{mass}}{M} \]
- Rearranging this gives us:
\[ M = \frac{\text{mass}}{n} = \frac{1.16 \text{ g}}{0.04464 \text{ moles}} \approx 25.984 \text{ g/mol} \]
- We can round this to approximately 26 g/mol.

4. **Compare with Given Options**:
- Now we will check the molar masses of the provided options to see which one matches approximately 26 g/mol:
- **C2H2 (Ethylene)**:
- Molar mass = \(2 \times 12 + 2 \times 1 = 24 + 2 = 26 \text{ g/mol}\) (Possible)
- **CO (Carbon Monoxide)**:
- Molar mass = \(12 + 16 = 28 \text{ g/mol}\) (Not possible)
- **O2 (Oxygen)**:
- Molar mass = \(2 \times 16 = 32 \text{ g/mol}\) (Not possible)
- **NH3 (Ammonia)**:
- Molar mass = \(14 + 3 \times 1 = 14 + 3 = 17 \text{ g/mol}\) (Not possible)

5. **Conclusion**:
- The only gas that has a molar mass close to 26 g/mol is **C2H2 (Ethylene)**. Therefore, the correct answer is option A.