Solve this:

42. A carnot heat engine has efficiency of 10%. If the same engine is worked backward to obtain a refrigerator, then coefficient of performance of the refrigerator is 

(1) 5           (2) 6
(3)  8          (4) 9

43. In a process, the molar heat capacity of a diatomic gas is $\frac{10R}{3}.$ When heat Q is supplied to the gas, then the work done by the as is.

$$\begin{gathered} \left(1\right) \frac{Q}{4} \\ \left(2\right) \frac{Q}{3} \\ \left(3\right) \frac{2Q}{3} \\ \left(4\right) \frac{3Q}{4} \end{gathered}$$