Because the hot air balloon is than the surrounding air, it will float:
A)less dense
B)more dense

A) Less dense

Explanation:

As air is heated, it becomes less dense than the surrounding cooler air. The less dense hot air has enough lifting power to cause the balloon to float and rise into the air.

I hope this makes sense.

it forms an anion that has a larger radius. anions have a negative charge and are larger than the original atom.