JEE Main · 2025 · 28 Jan 2025 · Shift 1 · d and f Block Elements

$N{i}^{2+}$ has the $d^8$ configuration $t_{2g}^6{e}_g^2$; in an octahedral field there is no alternative arrangement for eight d-electrons whether the ligand is weak- or strong-field, so its electronic configuration — and the magnetic/spectral behaviour that follows from it — is essentially unaffected by the identity of the ligand. In the borax bead test, the nickel metaborate formed under a hot, non-luminous (oxidising) flame gives the characteristic violet-coloured bead.