JEE Main · 2013 · 07 Apr 2013 · Offline · d and f Block Elements

Which of the following arrangements does not represent the correct order of the property stated against it?

Answer: (D)

Solution

Paramagnetism tracks the number of unpaired electrons:

V^{2 +} (d^{3}) = 3

C r^{2 +} (d^{4}) = 4

M n^{2 +} (d^{5}) = 5

, but

F e^{2 +} (d^{6}) = 4

. So

M n^{2 +} < F e^{2 +}

is false and option D is NOT a correct order. The others are correct: (A) ionic radii fall

M n^{2 +} > F e^{2 +} > C o^{2 +} > N i^{2 +}

; (B) aqueous stability of

M^{3 +}

rises

C o^{3 +} < F e^{3 +} < C r^{3 +} < S c^{3 +}

; (C) number of oxidation states rises

Sc < Ti < Cr < Mn

JEE Main · 2013 · 07 Apr 2013 · Offline · Single correct option