The temperature of 5 moles of a gas at constant volume is changed from `100^(@)C` to `120^(@)C`. The change in internal energy is 80 J. The total heat capacity of the gas at constant volume will be in `J/K.`

Options

A. 8
B. 4
C. `0.8`
D. `0.4`

Answer

B

Explanation

From `1^(st)` law of thermodynamics,
`dQ=dU + dW`
It is a constant volume process, `DeltaV=0`
`implies dW = pdv =0`
`dQ = dU`
`mSDeltat = (80//5)`
`S= (80)/(5xx20) = 0.8 J`
For 5 moles, `S= 0.8 xx 5= 4 J//K`