Question

A diatomic gas obeys the law $P{V}^x$= constant. For what value of x, it has negative molar specific heat?

• A. $0<x<1$
• B. $1<x<1.4$
• C. $x<1.4$
• D. $x>1.4$

Answer 1

The correct option is B

$1<x<1.4$

For diatomic gas, $C_V=\frac{5R}{2}$

Specific heat of polytropic process is $C=C_V+\frac{R}{1-x}=\frac{5R}{2}+\frac{R}{1-x}$

If x lies b/w 1 & 1.4, then C becomes –ve.

i,e, $1<x<1.4$