Is state change physical or chemical? Explain how you know.

Physical

Explanation:

State Change is physical because it changes without it being chemically done. So when water changes from a liquid to a solid the state of it is changing. (Solid or Liquid or Gas)

Basically what is physically being changed with out a chemical.

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

one negative thing it that it can kill water animals. another negative thing is it can cause the destruction of ecosystem. one way water pollution can be reduced is to conserve energy.