In a Bell Coleman Refrigeration plant, compression and expansion of air are isentropic. If the temperature of air entering and leaving the expander are 400 K and 200 K respectively then what will be the COP of the plant ? then what will be the COP of the plant ?

The correct answer is (b), 1.0.

The coefficient of performance (COP) of a refrigerator is defined as the ratio of the heat removed from the refrigerated space to the work input. In an ideal refrigerator, the COP is given by the following equation:

COP = $\frac{T_{L}}{T_{H} – T_{L}}$

where $T_{L}$ is the temperature of the refrigerated space and $T_{H}$ is the temperature of the heat source.

In this case, the temperature of the refrigerated space is 200 K and the temperature of the heat source is 400 K. Therefore, the COP is:

COP = $\frac{200}{400 – 200} = 1.0$

The other options are incorrect because they do not take into account the temperature of the refrigerated space and the heat source.