Which of these is not true? A. Atoms of the same elements can have different masses.
B. The nucleus of an atom has a positive charge.
C. Atoms have isotopes of an element have different numbers of protons.
D. Atoms are mostly empty space.

C. Atoms have isotopes of an element have different numbers of protons.

Explanation:

The isotopes are the variation in the number of neutrons (neutral charge), with increases the weight of the atom, so the first one, is related to this one.

C

Explanation:

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).