2.8 g of a gas at 1atm and 273K occupies a volume of 2.24 litres. The gas can not be:

Options

A. `O_(2)`
B. CO
C. `N_(2)`
D. `C_(2)H_(4)`

Answer

To solve the problem, we need to determine the identity of the gas based on the given conditions. We will use the Ideal Gas Law and the information provided to find the molar mass of the gas and then compare it with known gases.

### Step-by-Step Solution:

1. **Identify the Given Data**:
- Mass of gas (m) = 2.8 g
- Pressure (P) = 1 atm
- Temperature (T) = 273 K
- Volume (V) = 2.24 L

2. **Use the Ideal Gas Law**:
The Ideal Gas Law is given by the equation:
\[ PV = nRT \]
where:
- \( n \) = number of moles of gas
- \( R \) = ideal gas constant = 0.0821 L·atm/(K·mol)

3. **Calculate the Number of Moles (n)**:
Rearranging the Ideal Gas Law to solve for \( n \):
\[ n = \frac{PV}{RT} \]
Plugging in the values:
\[ n = \frac{(1 \, \text{atm})(2.24 \, \text{L})}{(0.0821 \, \text{L·atm/(K·mol)})(273 \, \text{K})} \]

4. **Calculate the Moles**:
\[ n = \frac{2.24}{(0.0821)(273)} \approx \frac{2.24}{22.413} \approx 0.1 \, \text{mol} \]

5. **Calculate the Molar Mass (M)**:
The molar mass can be calculated using the formula:
\[ M = \frac{m}{n} \]
where \( m \) is the mass of the gas and \( n \) is the number of moles.
\[ M = \frac{2.8 \, \text{g}}{0.1 \, \text{mol}} = 28 \, \text{g/mol} \]

6. **Identify Possible Gases**:
Now we need to identify gases with a molar mass of 28 g/mol. Common gases with this molar mass include:
- Nitrogen (N₂) = 28 g/mol
- Carbon monoxide (CO) = 28 g/mol

7. **Identify the Gas that Cannot Be**:
The question asks which gas cannot be the one described. We need to consider gases with molar masses different from 28 g/mol. For example:
- Oxygen (O₂) = 32 g/mol
- Carbon dioxide (CO₂) = 44 g/mol

Since the problem states that the gas cannot be one of these, we conclude that the gas cannot be oxygen (O₂) as it has a molar mass of 32 g/mol.

### Final Answer:
The gas cannot be **Oxygen (O₂)**.