Question

Heat is applied to a rigid diatomic gas at constant pressure. The ratio ΔQ : ΔU : ΔW is ______.

Options

• 7 : 5 : 2

• 5 : 2 : 7

• 5 : 7 : 2

• 2 : 5 : 7

Answer 1

Heat is applied to a rigid diatomic gas at constant pressure. The ratio ΔQ : ΔU : ΔW is 7 : 5 : 2.

Explanation:

dQ = dU + dW

CpdT = C_vdT + R dT

C_p = C_v + R

For a diatomic gas `"C"_"v" = 5/52 "R", "C"_"p" = 7/2 "R"`

`therefore ΔQ : ΔU : ΔW : : 7/2"R" : 5/2 "R" : "R" : : 7 : 5 : 2`