JEE Main 2022 · 29 Jul · Shift 2 · Chemistry Q70

ChemistrySingle correct+4 / -1Question 70 of 90

Which of the following 3d-metal ion will give the lowest enthalpy of hydration ( $\Delta_{hyd}H$ ) when dissolved in water ?

\mathrm{Cr^{2+}}

\mathrm{Mn^{2+}}

\mathrm{Fe^{2+}}

\mathrm{Co^{2+}}

Answer and worked solution

Official answer: B

CFSE. High-spin Mn²⁺ ( $d^5$ ) has zero crystal field stabilisation, so its hydration enthalpy is the least negative of these ions.

(B)

Topics:Transition element properties Crystal field theory

JEE Main 2022 · 29 Jul · Shift 2, Chemistry question 70