Anne Wittman, age 15, of Richmond, Va., for her question:

WHAT DO THEY PUT IN MOTHBALLS?

Once you've smelled a mothball, you'll never forget the odor. It's very distinctive.

Mothballs are small white or gray balls about the size of marbles. They are used to keep moths out of furs and fine fabrics. When fabrics are stored for long periods of time, mothballs are usually added for protection.

The distinctive odor comes from the material that makes the mothball, naphthalene. This useful product is a type of aromatic hydrocarbon.

It doesn't take a scientist to tell you why the moths stay away from a linen closet that has a few mothballs added to the stack of lace tablecloths. One sniff will tell you why.