A quantity of heat Q is supplied to a monoatomic ideal gas which expands at constant pressure. The fraction of heat that goes into work done by the gas `((W)/(Q))` is

Explanation

`C_(P)dT=C_(v)dT+dW, therefore dW=(C_(P)-C_(v))dT`
Fraction of heat converted into work
`(dW)/(dQ)=((C_(P)-C_(v))dT)/(C_(P)dT)=1-(C_(v))/(C_(P))=1-(1)/(gamma)`
For monoatomic gas, `gamma=5//3`
`therefore (dW)/(dQ)=1-(1)/(gamma)=1-(3)/(5)=(2)/(5)`,