Atoms X,Y,Z,and R have the following nuclear compositions:
Which two are isotopes?
A)X & Y
B)X & R
C)Y & R
D)Z & R
E)X & Z

Question

Atoms X,Y,Z,and R have the following nuclear compositions: 
Which two are isotopes?
A)X & Y 
B)X & R 
C)Y & R 
D)Z & R 
E)X & Z

Quizplus · Accepted Answer

Isotopes are atoms of the same element (same number of protons) with different numbers of neutrons. X and Z are isotopes because they have the same number of protons (both are the same element) but different numbers of neutrons. Y and R have different numbers of protons (and therefore are different elements) and are not isotopes.

Atoms X,Y,Z,and R Have the Following Nuclear Compositions