Which of the following statements is correct?

For a rigid diatomic molecule,the universal gas constant $R = n C_P$,where $C_P$ is the molar specific heat at constant pressure and $n$ is a number. Hence,$n$ is equal to

$70 \, cal$ of heat are required to raise the temperature of $2 \, moles$ of an ideal gas at constant pressure from $30^{\circ}C$ to $35^{\circ}C$. The amount of heat required to raise the temperature of the same gas through the same range ($30^{\circ}C$ to $35^{\circ}C$) at constant volume is ..... $cal$ $(R = 2 \, cal/mol \cdot K)$.

The specific heat at constant volume for the monoatomic argon is $0.075 \, kcal/kg-K$,whereas its gram molecular specific heat $C_V = 2.98 \, cal/mole/K$. The mass of the argon atom is (Avogadro's number $= 6.02 \times 10^{23} \, molecules/mole$)

In the case of a diatomic gas,the fraction of heat supplied at constant pressure that is used for the expansion of the gas is:

In a non-rigid diatomic molecule with an additional vibrational mode,what is the relationship between $C_v$ and $C_p$?