A cylinder with fixed capacity of 67.2 lit contains helium gas at STP. The amount of heat (in joule) needed to raise the temperature of the gas by `20^(@)C` is
[Given that `R=8.31J"mol"^(-1)K^(-1)`]

Explanation

To solve the problem, we need to determine the amount of heat required to raise the temperature of helium gas in a cylinder with a fixed capacity of 67.2 liters by 20°C. We will follow these steps:

### Step 1: Convert the volume of the gas to moles
At standard temperature and pressure (STP), 1 mole of an ideal gas occupies 22.4 liters. Therefore, we can calculate the number of moles (n) of helium gas in the cylinder using the formula:

\[ n = \frac{\text{Volume}}{22.4 \, \text{L/mol}} \]
...