Which of the following sets contain only isoelectronic ions?

Options

A. `Zn^(2+) , Ca^(2+) , Ga^(3+) ,A1^(3+)`
B. `K^(+) ,Ca^(2+) Sc^(3+) ,C1^(-)`
C. `P^(3-) , S^(2-), C1^(-) , K^(+)`
D. `Ti^(4+) , Ar, Cr^(3+) ,V^(5+)`

Answer

B, C

Explanation

Species of set (a)i.e., `Zn^(2+) (30-2 = 28 ) , Ca^(2+) (20 -2=18) , Ga^(3+) (31-3 = 28) , A1^(3+) (13 -3=10)`
have different no of electron and hence are not isoelectronic ions.
Species of set ( b) i.e., `K^(+) (19-1=18) ,Ca^(2+) (20-2 =18) , Sc^(3+) (21-3=18) ,C1^(-) (17+1=18) `are all isoelectron ions since each one of them has 18 electrons.
Species of set (c ) i.e., `P^(3-) (15+3 =18) ,S^(2-) (16+2 =18) ,C1^(-) (17+ 1=18) , K^(+) (19-1=18) ` are all isoelectron ions since each one of them has 18 electrons .
Species of set (d) i.e., `Ti^(4+) (22 -4 =18) ,Ar (18), Cr^(3+) (24-3=21) ,V^(5+) (23 -5= 18)` have different number of electron and hence are not isoelectronic ions.