Answer:
Mg > Al > P > Cl > Ar
Explanation:
Mg / P / Cl / Al / Ar
The tendency of atomic radia is that the higher the period, the higher the radius; and that the higher the group, the smaller the radius.
- Mg is the furthest left and down between the options, so that's the largest one.
- Just right of Mg there's Al, so that's the next one.
- Going by the tendency, the next ones should be P and Cl.
- Ar is the furthest right, so that's the smallest one.
