The statement(s) that are correct about the species O2-, F-, Na+ and Mg2+. Choose the most appropriate answer from the options given below :
- C and D only
- A, C and D only
- B, C and D only
- A, B, C and D
Answer
(2) A, C and D only
Solution
Species: O2- (Z = 8), F- (Z = 9), Na+ (Z = 11), Mg2+ (Z = 12)
A: electrons: O2- 8 + 2, F- 9 + 1, Na+ 11 − 1, Mg2+ 12 − 2 ⇒ all have 10 ⇒ A is correct
B: nuclear charge = Z, different for each ⇒ B is wrong
∵ for isoelectronic ions, radius ∝ 1nuclear charge
⇒ ionic radius: O2- > F- > Na+ > Mg2+ ⇒ C and D are correct
Answer: (2)