What happens to a substance when it is heated? a
Thermal energy is decreased
b
Potential energy is increased
c
Kinetic energy is increased
d
It does not change its physical shape

C

Explanation:

When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster:  the space between atoms increases:   The motion and spacing of the particles determines the state of matter of the substance:  The end result of increased molecular motion is that the object expands and takes up more space.

they float because they are less dense than the water itself

something denser than water, like a rock, will sink to the bottom

where is the option.let me know