The main specialization of Area 51 is to be used as a facility for flight testing and aircraft for the U.S. Air Force.
Its called a double replacement/displacement reaction.
The answer to your question is the third, fifth, and eighth sentence.
Answer:
Convection current
Explanation:
Convection currents occur when a heated fluid expands, becoming less dense, and rises. The fluid then cools and contracts, becoming more dense, and sinks
Hot air rises because when you heat air (or any other gas for that matter), it expands. When the air expands, it becomes less dense than the air around it. The less dense hot air then floats in the more dense cold air, the cold air due to its greater density moves downward, and the cycle continues, this upward and downward movement is called convection current.
