JEE Main 2025 Jan 29 Shift 2, Chemistry Q21: Colour, Magnetism And Stability Of Co-ordination Compounds

JEE Main2025Jan 29, Shift 2Chemistry

Consider the following low-spin complexes

$K_{3} [C o (N O_{2})_{6}]$ , $K_{4} [F e (C N)_{6}]$ , $K_{3} [F e (C N)_{6}]$ , $C u_{2} [F e (C N)_{6}]$ and $Z n_{2} [F e (C N)_{6}]$ .

The sum of the spin-only magnetic moment values of complexes having yellow colour is _______ B.M. (answer is nearest integer)

Your answer

Solution

Identify the yellow members of the list and compute $μ = n (n + 2)$ for each.

$K_{3} [C o (N O_{2})_{6}]$ : $C o^{3 +}$ , $d^{6}$ low-spin, $n = 0$ . Yellow. $μ = 0$ .

$K_{4} [F e (C N)_{6}]$ : $F e^{2 +}$ , $d^{6}$ low-spin, $n = 0$ . Yellow. $μ = 0$ .

$K_{3} [F e (C N)_{6}]$ : $F e^{3 +}$ , $d^{5}$ low-spin, $n = 1$ . Colour is red-orange (not yellow), so excluded.

$C u_{2} [F e (C N)_{6}]$ : chocolate/brown solid, excluded.

$Z n_{2} [F e (C N)_{6}]$ : white solid, excluded.

Sum of $μ$ for the yellow complexes $= 0 + 0 = 0$ B.M.

Concept behind this question

Concept-wise practice with instant solutions on Fundamenthol.