Question

Explain why a balloon expands when taken to a higher elevation if the temperature remains constant?

Answer 1

B) The decrease in atmospheric pressure relative to pressure inside the balloon causes it to expand.

Answer 2

Boyle said that, if temperature of ideal gas is kept constant then pressure and volume of ideal gas are inversely proportional to each other.

Pα1/V
Pressure decreases with elevation therefore volume of balloon increases.