Final answer:
Cumyl peroxide, an organic peroxide, is a chemical that requires refrigeration in an explosion-proof refrigerator due to its volatility and explosive risk. Option d is the answer.
Step-by-step explanation:
The question pertains to the safe storage of chemicals, specifically which chemicals would require refrigeration in an explosion-proof refrigerator. An explosion-proof refrigerator is necessary for storing volatile or highly reactive chemicals that may pose a risk of explosion if there are any leaks or sparks. Among the listed options, cumyl peroxide (solid) is known to be an organic peroxide, which is a temperature-sensitive substance that can pose an explosive hazard. It must be stored at low temperatures to ensure stability and must be kept in an explosion-proof refrigerator to mitigate any potential risks due to its volatility.