JEE Main 2026 — Apr 2, Shift 2 — Chemistry solution

JEE Main2026Apr 2, Shift 2Chemistry

Given below are two statements :

Statement-I : Among Zn, Mn, Sc and Cu, the energy required to remove the third valence electron is highest for Zn and lowest for Sc.

Statement-II : The correct order of the following complexes in terms of CFSE is $[Co(H_{2} O)_{6}]^{2 +} < [Co(H_{2} O)_{6}]^{3 +} < [Co(en)_{3}]^{3 +}$ .

In the light of the above statements, choose the correct answer from the options given below :

A
Both Statement-I and Statement-II are true.
B
Both Statement-I and Statement-II are false.
C
Statement-I is true but Statement-II is false.
D
Statement-I is false but Statement-II is true.

Solution

Statement-I: The third ionisation energies (kJ/mol) are Sc $\approx 2393$ , Mn $\approx 3260$ , Cu $\approx 3556$ , Zn $\approx 3837$ . So the order Sc $<$ Mn $<$ Cu $<$ Zn holds — IE $_{3}$ is lowest for Sc and highest for Zn. $✓$

Statement-II: CFSE depends on (i) the ligand-field strength (en is stronger than H $_{2}$ O on the spectrochemical series) and (ii) the metal oxidation state (higher charge $\Rightarrow$ larger $Δ_{o}$ ). Both factors increase CFSE in the given order:

$[Co(H_{2} O)_{6}]^{2 +}$ (low charge, weak field) $< [Co(H_{2} O)_{6}]^{3 +}$ (high charge, weak field) $< [Co(en)_{3}]^{3 +}$ (high charge, strong field). $✓$

Both statements are true.

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