Question

Each of the models shown represents a magnesium atom.



Which models show the same isotope of magnesium?
A.

P and Q

B.

P and R

C.

Q and R

D.

P, Q, and R

Answer 1

C. Q and R

Isotopes are atoms of the same element (same number of protons) with different numbers of neutrons. All three are magnesium (same protons), but Q and R have the same number of neutrons (same mass number), so they are the same isotope.