JEE Main 2025 Apr 7 Shift 2, Chemistry Q10: d-Block Elements

JEE Main2025Apr 7, Shift 2Chemistry

'X' is the number of acidic oxides among VO $_{2}$ , V $_{2}$ O $_{3}$ , CrO $_{3}$ , V $_{2}$ O $_{5}$ and Mn $_{2}$ O $_{7}$ . The primary valency of cobalt in [Co(H $_{2}$ NCH $_{2}$ CH $_{2}$ NH $_{2}$ ) $_{3}$ ] $_{2}$ (SO $_{4}$ ) $_{3}$ is Y.

The value of X + Y is :

Solution

Among the given vanadium and manganese oxides, acidic character increases with the oxidation state of the metal. CrO $_{3}$ (Cr in +6) and Mn $_{2}$ O $_{7}$ (Mn in +7) are clearly acidic oxides since the metal is in a very high oxidation state, while VO $_{2}$ , V $_{2}$ O $_{3}$ and V $_{2}$ O $_{5}$ are treated as basic/amphoteric here. Taking the two unambiguous acidic oxides, X = 2.

In [Co(en) $_{3}$ ] $_{2}$ (SO $_{4}$ ) $_{3}$ , two complex cations balance three SO $_{4}^{2 -}$ ions, so each complex cation carries a charge of +3. Ethylenediamine (en) is a neutral ligand, so the entire +3 charge is the oxidation state of cobalt, which is also its primary valency: Y = 3.

$∴$ X + Y = 2 + 3 = 5.

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JEE Main 2025 Apr 7 Shift 2, Chemistry Q10: d-Block Elements

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