For an ideal diatomic gas,f process equation is $P=b{V}^a$  (P = Pressure, V = volume, b and a are positive constants). If molar specific heat of process is zero then value of a is

• A

  $a=-\raisebox{1ex}{$5$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$

• B

  $a=\raisebox{1ex}{$5$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$

• C

  $a=\raisebox{1ex}{$7$}\!\left/ \!\raisebox{-1ex}{$5$}\right.$

• D

  $a=-\raisebox{1ex}{$7$}\!\left/ \!\raisebox{-1ex}{$5$}\right.$