Cesium-137 has a half-life of 30.3 years. If you start with 60g, how much cesium would be left over 90.9 years?

In the particles are arranged in a regular, repeating pattern. a)a crystalline liquid b)a crystalline solid c)all gases d)all solids

This chart lists four kinds of polymers and their sources. what can be known about all four polymers, despite their differences? they come from living things. they share ionic carbon bonds. they are at least 100 monomers long. they are made of repeating subunits.

In 2002, the rare earth elements mine in mountain pass, california was closed because