There are only 90 naturally occurring elements on Earth, but there are millions of different substances. Explain how this is
possible and describe how it applies to at least three examples.

Imagine that you have produced several versions of lactase, each of which differs from normal lactase by a single amino acid. describe a test that could indirectly determine which of the versions significantly alters the three-dimensional shape of the lactase protein.

Choose all the answers that apply. as ocean depth increases, temperature decreases temperature increases pressure increases pressure decreases salinity increases density increases

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.