A Carnot refrigerator works in temperature range of 300 K to 270 K with different refrigerants CFC, R – 32 and ammonia. Which of the refrigerant give better COP?

Correct option is D

​$$\begin{aligned}&\text{The \textbf{Coefficient of Performance (COP)} of a \textbf{Carnot refrigerator} is given by:} \\&\boxed{\text{COP}_{\text{Carnot}} = \frac{T_L}{T_H - T_L}} \\[1.5em]&\text{Where:} \\&T_L = \text{Lower temperature reservoir} = 270\, \text{K} \\&T_H = \text{Higher temperature reservoir} = 300\, \text{K} \\[1.5em]&\text{COP}_{\text{Carnot}} = \frac{270}{300 - 270} = \frac{270}{30} = \boxed{9}\end{aligned}$$​​

The COP of a Carnot refrigerator depends only on the temperatures of the heat reservoirs.
It is independent of the working substance or refrigerant.
So whether the refrigerant is:
CFC (chlorofluorocarbon)
R-32 (Difluoromethane)
Ammonia (NH₃)
The Carnot COP remains the same since the operating temperature limits are the same.