Question

The ratio of Cp / Cv is always -----1 :
a) greater than 1
b) less than 1
c) equal to 1
d) none of these

Answer 1

$\sf\large{\underline{\underline{Answer :}}}$

(a) greater than 1

$\sf\large{\underline{\underline{Explaination :}}}$

As per the first law of Thermodynamics,

dQ = dU + dW (Assuming usual notations)

From the definitions of cp and cv

in a constant pressure (isobaric) and constant volume(isochoric) process respectively,

dQp = m.cp.dT

dQv = m.cv.dT

In a constant volume process , dW = 0 where as in a constant pressure work is done

Hence, dQp > dQv

Since cp and cv are proportional to dQp and dQv respectively we can say that cp > cv