A gaseous mixture consists of $7 \mathrm{~g}$ of nitrogen and $20 \mathrm{~g}$ of argon. Assume gases to be ideal. The specific heat capacities $C_{V}$ and $C_{P}$ in $\mathrm{J} / \mathrm{g}-\mathrm{K}$ for gaseous mixture are :
(a) $C_{P}=0.66 \mathrm{~J} / \mathrm{g}-\mathrm{K}, \mathrm{C}_{V}=18.25 \mathrm{~J} / \mathrm{g}-\mathrm{K}$
(b) $C_{P}=1.66 \mathrm{~J} / \mathrm{g}-\mathrm{K}, \mathrm{C}_{V}=1.82 \mathrm{~J} / \mathrm{g}-\mathrm{K}$
(c) $C_{P}=0.421 \mathrm{~J} / \mathrm{g}-\mathrm{K}, \mathrm{C}_{V}=15.2 \mathrm{~J} / \mathrm{g}-\mathrm{K}$
(d) $C_{P}=0.65 \mathrm{~J} / \mathrm{g}-\mathrm{K}, \mathrm{C}_{V}=0.421 \mathrm{~J} / \mathrm{g}-\mathrm{K}$