If for hydrogen Cp – Cv = a and for oxygen Cp – Cv = b, where Cp and Cv refer to specific heats at constant pressure and at constant volume then

Q: If for hydrogen C_p – C_v = a and for oxygen C_p – C_v = b, where C_p and C_v refer to specific heats at constant pressure and at constant volume then

(a) a = b

(b) a = 16b

(c) b = 16a

(d) a and b are not related

Ans: (b)

Sol: Relation between specific heat per unit mass , C_p – C_v = r = R/M , here M = molecular weight

For hydrogen gas C_p – C_v  = a = R/M = R/2   …(i)

for oxygen gas , C_p – C_v  = b = R/32  …(ii)

On dividing , a/b = 16