Refrigerators and air conditioners use a substance known as a "refrigerant" to absorb heat. Some of the first cooling systems used carbon dioxide and other naturally occurring chemicals as refrigerants, but these chemicals were not ideal for small cooling applications.

Question

How did engineers solve this problem and make small-scale refrigerators and air conditioners possible?
A.
by capturing oxygen gas from the atmosphere
B.
by bringing liquid water below its freezing point
C.
by using a compression system to compress carbon dioxide into a liquid
D.
by developing new chemicals with new properties

Answer 1

The correct answer is:

D. by developing new chemicals with new properties

Engineers solved the problem of creating effective refrigerants for small-scale refrigerators and air conditioners by developing synthetic chemicals that had desirable properties for refrigeration, such as low toxicity, low flammability, and efficient heat absorption and release. These new refrigerants, such as chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs), offered better performance and safety compared to earlier natural refrigerants.