0.5 litres of an ideal gas is present at a pressure.

Answer

To solve the question regarding the pressure of an ideal gas given its volume, we will use the Ideal Gas Law equation, which is:

\[ PV = nRT \]

Where:
- \( P \) = Pressure (in atm)
- \( V \) = Volume (in liters)
- \( n \) = Number of moles of the gas
- \( R \) = Universal gas constant (0.0821 L·atm/(K·mol))
- \( T \) = Temperature (in Kelvin)

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Volume \( V = 0.5 \) liters
- Number of moles \( n = 1 \) mole (assuming ideal conditions)
- Universal gas constant \( R = 0.0821 \) L·atm/(K·mol)
- Temperature \( T = 273 \) K (standard temperature)

2. **Substitute the Values into the Ideal Gas Law:**
We need to find the pressure \( P \). Rearranging the Ideal Gas Law gives us:
\[ P = \frac{nRT}{V} \]

3. **Plug in the Values:**
\[ P = \frac{(1 \, \text{mol}) \times (0.0821 \, \text{L·atm/(K·mol)}) \times (273 \, \text{K})}{0.5 \, \text{L}} \]

4. **Calculate the Numerator:**
\[ P = \frac{(1) \times (0.0821) \times (273)}{0.5} \]
\[ P = \frac{22.4143}{0.5} \]

5. **Calculate the Pressure:**
\[ P = 44.8286 \, \text{atm} \]
Rounding to two decimal places gives:
\[ P \approx 44.83 \, \text{atm} \]

### Final Answer:
The pressure of the ideal gas is approximately **44.83 atm**.

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