The time it takes for an ice cube to go from room temperature to freezing point can vary depending on several factors, including the initial temperature of the ice cube and the surrounding environment. Generally, a typical ice cube will start to melt and gradually cool down to the freezing point as it absorbs heat from its surroundings.
If left in a refrigerator overnight without power, the ice cube will eventually reach the temperature of the refrigerator, which is usually around 2-4 degrees Celsius (36-39 degrees Fahrenheit). However, it is unlikely to reach the freezing point (0 degrees Celsius or 32 degrees Fahrenheit) unless the refrigerator is exceptionally cold or the ice cube is extremely small.
As for freezer burn, it is a condition that occurs when frozen food is exposed to air, causing dehydration and the development of dry, discolored patches on the surface. Freezer burn is primarily a result of air exposure rather than temperature fluctuations. If the ice cube is properly sealed or covered, it is unlikely to experience freezer burn, even if the freezer loses power overnight.
It's worth noting that these timeframes and conditions can vary depending on the specific refrigerator or freezer, the size and composition of the ice cube, and other factors.