Which of the following statements is correct?

The specific heat of a gas:

$A$ cylinder with fixed capacity of $67.2 \, L$ contains helium gas at $STP$. The amount of heat needed to raise the temperature of the gas by $20 \, ^oC$ is ..... $J$ [Given that $R = 8.31 \, J \, mol^{-1} \, K^{-1}$]

Obtain the value of $\frac{C_P}{C_V}$ for a non-linear triatomic gas.

When a monoatomic gas is heated at constant pressure,what fraction of the heat energy supplied is used to increase the internal energy?

$50 \, cal$ of heat is required to raise the temperature of $1 \, mol$ of an ideal gas from $20^{\circ} C$ to $25^{\circ} C$,while the pressure of the gas is kept constant. The amount of heat required to raise the temperature of the same gas through the same temperature range at constant volume is ........ $cal$ $(R = 2 \, cal / mol \cdot K)$.