How much water in on the earth?

 It's roughly 326 million cubic miles (1.332 billion cubic kilometers), according to a recent study from the U.S. Geological Survey. Some 72 percent of Earth is covered in water, but 97 percent of that is salty ocean water and not suitable for drinking.

Explanation: Hope this helps

326 million trillion gallons of water on Earth.

97.5% is salt water

2.5% is fresh water

Explanation:

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.