A gas has molar heat capacity `C = 4.5 R` in the process `PT = constant`. The number of degrees of freedom of molecules in the gas is

Options

A. 4
B. 3
C. 6
D. 5

Answer

D

Explanation

PT=const. . . (1)
`(T^(n))/(P^(n+1))=`const.
`P^(1-n)T^(n)`=const.
`PT^((n)/(1-n))=`const. . . (2)
By equation (1) & (2)
`implies (n)/(1-n)impliesn=(1)/(2)`
`C_("poly")=C_(V)+(R)/(1-n)`
`implies4.5R=(f)/(2)R+(R)/(1-(1)/(2))implies f=5`