N moles of an ideal diatomic gas are in a cylinder at temperature T. suppose on supplying heat to the gas, its temperature remain constant but n moles get dissociated into atoms. Heat supplied to the gas is

Options

A. Zero
B. `1/2nRT`
C. `2/3nRT`
D. `3/2 (N-n)RT`

Answer

B

Explanation

`U_(i) =5/2 NRT and `
`U_(f) =5/2 (N-n) RT+3/2 (2n)RT`
`V=` constant `impliesDelta W =0implies Delta Q =dU`
`Delta Q =U_(f) -U_(i)`
`=5/2 (N-n) RT+3/2(2n) RT-5/2 NRT`
`Delta Q =1/2 nRT`