Which of the following statements is true?
a. calcium and potassium are good for your body.
b. most of the atmosphere is made of oxygen and helium.
c. the center of an atom is made of protons and electrons.
d. all of the above.

Seltzer water is created by placing water under pressure with carbon dioxide gas. which of the following statements best describe seltzer water: a. the solution will be slightly acidic b. the solution will be slightly basic. the solution will be strongly acidic. d. the solution will be strongly basic. e. the solution will be neutral

The climate of the continental united states is generally 1. tropical 2. temperate 3. arctic 4. highland

1. list three scientific reasons cockroaches may fly.