How many joules are in 1 kilojoule?

One kilojoule is defined as 1,000 joules. This relationship is based on the metric system where the prefix "kilo-" signifies a factor of one thousand. Therefore, when converting kilojoules to joules, you multiply the number of kilojoules by 1,000 to arrive at the equivalent amount in joules. In this case, 1 kilojoule equals 1,000 joules, making this choice the correct answer.

Understanding this conversion is essential in refrigeration and thermal systems, where energy measurements are often expressed in both joules and kilojoules. The ability to accurately convert between these units can be vital for calculations involving heat transfer, energy consumption, and system efficiencies in refrigeration processes.