c
(c)$\eta = \frac{{{T_1} - {T_2}}}{{{T_1}}} = \frac{W}{Q}$
==> $W = \frac{{Q({T_1} - {T_2})}}{{{T_1}}}$
$ = \frac{{6 \times {{10}^4}\left[ {(227 + 273) - (273 + 127)} \right]}}{{(227 + 273)}}$
$ = \frac{{6 \times {{10}^4} \times 100}}{{500}}$$ = 1.2 \times {10^4}cal$