Should someone who lives on the sixth floor of an apartment building be concerned about radon in his or her apartment? why or why not?

The person should not be concerned about radon.

Explanation:

A person living on the sixth floor of an aparment probably should not be concerned about radon. In the conditions of the Earth's atmosphere (temperature and pressure), radon exists as a gas. This gas has a density that is approximately 8 times higher than the density of air (9.73 g/L compared to 1.22 g/L). This means that radon gas would not rise, and instead remain close to the ground, meaning that an apartment on a sixth floor is too far away from the ground for radon gas to reach there.

A gas being denser than air is also the reason why if you blow into a balloon, it will fall to the ground, because CO₂ is denser than air.