What is the definition of a covalent bond?
a. a bond between a positive and negative ion
b. a bond between two negative ions
c. a bond betwen two positive ions
d. a bond between two atoms?

Nonpoint source pollution is difficult to control because it

Upon decomposition, one sample of magnesium fluoride produced 1.65 kg of magnesium and 2.56 kg of fluorine. a second sample produced 1.32 kg of magnesium. part a how much fluorine (in grams) did the second sample produce?

What causes different colors to appear in the sky? the absorption of light by air molecules the reflection of light by bodies of water the greenhouse effect in earth's atmosphere the scattering and reflection of light by dust particles