The specific heat of helium at constant volume is `12.6 Jmol^(-1)K^(-1).` The specific heat of helium at constant pressure in `Jmol^(-1)K^(-1)` is about
(Assume the temperature of the gas is moderate, universal gas constant, `R=8.314 J mol^(-1)K^(-1)`

Options

A. 12.6
B. 16.8
C. 18.9
D. 21

Answer

D

Explanation

`C_(v)=12.6 J mol^(-1)K^(-1)`
`C_(p) = ?`
`C_(p) - C_(v) = R`
`implies` `C_(p) = 12.6 + 8.314`
`therefore` `C_(p) =` 20.914 ` cong` 21