CBSE 2025 · Region 2 · Set 1 · Q25 · 3 marks

Using valence bond theory, explain the hybridization and magnetic character of the following : $\displaystyle \mathbf{2} \times \mathbf{1} \frac{\mathbf{1}}{\mathbf{2}}=\mathbf{3}$

(a)

$\displaystyle \left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$

(b)

$\displaystyle \left[\mathrm{Ni}(\mathrm{CO})_{4}\right]$ [At. no. : $\displaystyle \mathrm{Co}=27, \mathrm{Ni}=28$ ]

CBSE Class 12 Chemistry past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.