c
\({T_B}\,\, = \,\,{T_1}\,,\,{T_C}\,\, = \,\,{T_2},\,\gamma \,\, = \,\,1.4,\,{V_B}\,\, = \,\,V,\,\,{V_C}\,\, = \,32V\)

\( \Rightarrow {T_B}V_B^{\gamma  - 1}\,\, = \,\,{T_C}V_C^{\gamma  - 1} \Rightarrow \frac{{{T_C}}}{{{T_B}}}\,\, = \,\,\frac{{{T_2}}}{{{T_1}}}\,\, = \,\,{\left( {\frac{{{V_B}}}{{{V_C}}}} \right)^{\gamma  - 1}}\)

\( = \,\,{\left( {\frac{1}{{32}}} \right)^{\gamma  - 1}}\,\, = \,\,\frac{1}{4}\,\,\,\therefore \,\,\,\eta \,\, = \,\,1 - \frac{{{T_2}}}{{{T_1}}}\,\, = \,\,1 - \frac{1}{4}\,\, = \,\,\frac{3}{4}\,\, = \,\,0.75\)