The number of electrons, neutrons, and protons in four different particles, W, X, Y, and Z, are shown in the table below.
| Particle | Electrons | Neutrons | Protons |
|---|---|---|---|
| W | 18 | 22 | 20 |
| X | 18 | 20 | 18 |
| Y | 10 | 10 | 9 |
| Z | 10 | 12 | 10 |
Explain which particle, W, X, Y, or Z, is a positive ion.
