How many calories are required to heat `40 g` of argon from `40^(@)C` to `100^(@)C` at constant volume? `(R = 2 cal mol^(-1) K^(-1))`

Options

A. `120`
B. `2400`
C. `1200`
D. `180`

Answer

D

Explanation

For a monoatomic gas like argon, `C_(V)=3 kcal mol^(-1)`, `C_(P)=5cal mol^(-1)`. Molar heat capacity is the heat required to raise the temperature of `1` mole of the gas by `1^(@)`.
`40 g` of argon `=1` mole.Hence , heat required to raise the temperature from `40^(@)` to `100^(@)C` at constant volume `=3xx(100-40)=180cal`