If a gas is heated at constant pressure, then what percentage of total heat supplied is used up of external work ? (r=4/3)

If a gas is heated at constant pressure, then what percentage of total

1.	If a gas is heated at constant pressure, then what percentage of total heat supplied is used up of external work ? (r=4/3)
Answer» `25%` `50%` `75%` `80%` Solution :PV=nRT Gas is heated at constant pressure, `PDeltaV=nRDeltaT` `THEREFORE DeltaW=nRDeltaT` ….(1) heat given to the gas, `DeltaQ=eta C_P DeltaT` …(2) `therefore` By TAKING ratio of equ. (1) and (2), `(DeltaW)/(DeltaQ)=(nRDeltaT)/(nC_P DeltaT)=R/C_P` `=(C_P-C_V)/C_P [because R=C_P=C_V]` `=C_P/C_V-C_V/C_P` `=1-1/gamma` `=1-3/4` `=1/4` =25%