Glenn Parker, age 11, of Niagara Falls, Ontario, Canada, for his question:

How does an atom compare with an inch?

Atoms come in various sizes, somewhat like buildings that range from small homes to skyscrapers. The iron atom is one of medium size. Scientists have estimated that a rox Y of about 100 million iron atoms measure one inch. In real life, of course, it is not possible to pack a row of atoms shoulder to shoulder. Even in the densest solids there are spaces between them.

Besides, no human mind can grasp a number as big; as 100 million individual atoms. But there are other estimates that make it easier to imagine their infinitesimal sizes. One compares an atom with a pinprick and a mile. If their sizes are increased at the same rate, the atom would be as big as a pinhole when the pinhole is a mile wide.