Why was 1990 an important year regarding air quality? O The United States took first steps to keep the air clean.
O The United States created the Environmental Protection Agency.
Modifications and improvements were made to the Clean Air Act.
O Funding was established under the Clean Air Act to study air pollution.

Of the groups of elements below, which are most likely to gain electrons to become anions? a. alkali metal b. boron group c. halogen d. transition metal

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

If we compare and contrast electromagnetic waves with sound waves, all but one statement is true. that is a) sound waves require a medium to travel while electromagnetic waves do not. b) electromagnetic waves can travel through the vacuum of space while sound waves cannot. c) electromagnetic waves must have a medium in which to travel, but sound waves can travel anywhere. eliminate d) sound waves must bounce off of matter in order to travel while electromagnetic waves do not require matter to be present.