If for hydrogen Cp – Cv = m and for nitrogen Cp- Cv = n, where Cp and Cv refer to specific heats per unit mass respectively….

Q: If for hydrogen C_p – C_v = m and for nitrogen C_p– C_v = n, where Cp and C_v refer to specific heats per unit mass respectively at constant pressure and constant volume, the relation between m and n is (molecular weight of hydrogen = 2 and molecular weight of nitrogen = 14)

(a) n = 14m

(b) n = 7 m

(c) m = 7n

(d) m = 14n

Ans: (c)

Solution : Molar Specific heat = Molar mass × Specific heat

2(C_p – C_v)= R

2 m = R …(i)

14(C_p – C_v) = R

14 n = R …(ii)

From (i) and (ii)

2 m = 14 n

m = 7 n