Susan Frasier., age 13, of Oak Hill, W, Va., for her questions

What is liquid oxygen?

At ordinary temperatures, pure oxygen is a gas. However, it readily combines with outer elements to form solids and liquids. It forms nearly half the weight of the rocks in the earth's crust. Eight ninths of every pound of water is oxygen   but this is not liquid oxygen.

When the temperature gets around minus 183 degrees Centigrade, oxygen is below its boiling point, It then becomes a liquid. If the temperature keeps on falling to minus 218 degrees, oxygen will reach its freezing point and become solid. Nowadays, liquid oxygen, called LOX for short, is very much in the news, it is one of the chemical mixed with rocket fuels  to launch some of our  rockets.