When an object is heated, its molecules . 1.move faster
2.slow down
3.stop moving
4.do not change at all

When an object is heated, its molecules move faster and bounce off each other.

Explanation:

Smoke detectors

Explanation:

This is because the ionization chamber in smoke detectors uses radiation, a form of heat transfer to detect smoke.

.The NRC allows beneficial use of smoke detectors which is a radioactive material because a smoke detector has the ability to save lives . it's ability to save lives outweighs any health risk from the radiation. The smoke detector use a very minimal amounts of radioactive materials.