As the air molecules move through the valve they have friction as they hit the walls, and its this friction that causes it to heat up.
Answer:
Its b its the state not anything else
D, they can be renewed quickly rather than non renewables in which nonrenewable take millions of years. Biomass is all around us, so is water (hydro) and the sun is around us too.
The air in the sky and the clouds are gas, however some things in the sky [such as the sun/moon] are solid.
Hope that helped!
