What energy conversion occurs when a battery powered car rolls across the floor ?

The battery itself contains chemical energy, which is converted to electrical energy, and then converted to mechanical energy. 

The battery stored in chemical energy . which is converted to electrical energy which is converted to mechanical energy. a electrical energy is not stored in batteries but rather in capacitors.

False, as a substance changes from a solid to a liquid and from a liquid to a gas the molecules get farther apart from each other

The answer is solid copper