When an ideal gas (\(\gamma = \frac{5}{3}\)) is heated under constant pressure, what percentage of given heat energy will be utilized in doing external work ? 

25%

\(\frac{\Delta W}{\Delta Q} = \frac{\Delta Q - \Delta U}{\Delta Q}\)

\(\frac{\Delta W}{\Delta Q} = \frac{C_P - C_V}{C_P}\)

\(\frac{\Delta W}{\Delta Q} = 1 - \frac{1}{\gamma}\)

\(\frac{\Delta W}{\Delta Q} = 1 - \frac{1}{\frac{4}{3}}\)

\(\frac{\Delta W}{\Delta Q} = \frac{1}{4}\)

i.e. percentage energy utilized in doing external work = \(\frac{1}{4}\) x 100 = 25%