ANS:C - 50 kJ/sec.

The statement "50 kJ/sec" refers to the rate of heat transfer, specifically 50 kilojoules per second. In the context of refrigeration, it indicates the amount of energy transferred per unit of time. Here's an explanation:

• Kilojoules (kJ): Kilojoule is a unit of energy in the International System of Units (SI). It is equivalent to 1000 joules. Joule is the standard unit of energy, representing the amount of energy transferred or expended when a force of one newton acts over a distance of one meter.
• Per second (sec): This indicates the time interval over which the energy transfer occurs. In this case, it's per second, meaning 50 kilojoules of energy are transferred every second.

In refrigeration systems, the rate of heat transfer, often measured in kilowatts (kW) or kilojoules per second (kJ/sec), represents the cooling capacity of the system. It indicates how much heat energy is removed from the cooled space per unit of time, reflecting the system's ability to maintain the desired temperature.