Among the elements Ca, Mg, P and Cl, the order of increasing atomic radii is
- Mg < Ca < Cl < P
- Cl < P < Mg < Ca
- P < Cl < Ca < Mg
- Ca < Mg < P < Cl
Answer
(2) Cl < P < Mg < Ca
Solution
Atomic radius decreases across a period (increasing effective nuclear charge) and increases down a group.
Mg, P and Cl are in period 3 ⇒ Cl < P < Mg.
Ca lies below Mg in group 2 ⇒ Mg < Ca.
As per NCERT, atomic radii (pm): Cl = 99, P = 110, Mg = 160, Ca = 197.
∴ Cl < P < Mg < Ca
Answer: (2)