Paul Driscoll, age 10, of Scarborough, Me., for his question:

EXACTLY WHAT IS WATER MADE OF?

When you eat a piece of cake, you might never suspect that it is made from flour and eggs, sugar and a few other ingredients. When you look at a drop of water, you might never suspect that its basic ingredients are two invisible gases. Actually, this is a chemical miracle, down there in the invisibly small realm of atoms and molecules. When atoms combine to form molecule packages, the original ingredients disappear and the finished product is something quite different.

There are, of course, zillions of mini molecules in just one drop of water. Each basic particle is a bond of two atoms of hydrogen and one atom of oxygen. Usually a water molecule is a pair of these basic particles. The packages team together because a hydrogen atom seeks an extra electron and an oxygen atom seeks two. They solve their problems by bonding together to share their electrons. In any case, water is made from one part oxygen and two parts hydrogen  both of which are invisible gases.