The numbers of subatomic particles present in four species W, X, Y and Z are given in the table.
| Species | Number of protons | Number of neutrons | Number of electrons |
|---|---|---|---|
| W | 19 | 20 | 18 |
| X | 19 | 20 | 19 |
| Y | 20 | 20 | 18 |
| Z | 20 | 22 | 20 |
Which of these species are isotopic?
Choose your answer
W and X
W and Y
X and Z
Y and Z

