In a popular classroom demonstration, a cotton ball is placed in the bottom of a strong test tube. A plunger fits inside the tube and it makes an air - tight seal. It is then pushed down very rapidly, and the cotton flashes and burns. This happens because
A) when the air was compressed its temperature increased.
B) friction between the plunger and the tube ignited the cotton.
C) cotton contains a pressure - sensitive substance that burns upon impact.
D) it's one of those demos that nobody understands.

Question

Quizplus · Accepted Answer

When the air is compressed rapidly by the plunger, its temperature increases significantly due to the compression of gas, which can ignite the cotton ball. This is a demonstration of the principle that compressing a gas increases its temperature, which is related to the ideal gas law.

In a Popular Classroom Demonstration, a Cotton Ball Is Placed