In which of the following pairs are both the ions coloured in aqueous solution ?
(At. no. : $Sc = 21, Ti = 22, Ni = 28,$$ Cu = 29, Co = 27$)
$Ni^{2+}, Cu^+$
$Ni^{2+}, Ti^{3+}$
$Sc^{3+}, Ti^{3+}$
$Sc^{3+}, Co^{2+}.$
Mercury is transported in metal containers made of
The $3d$ metal ions form coloured compounds because the energy corresponding to the following lies in the visible range of electromagnetic spectrum
Consider the following reaction
$\mathrm{MnO}_2+\mathrm{KOH}+\mathrm{O}_2 \rightarrow \mathrm{A}+\mathrm{H}_2 \mathrm{O} .$
Product ' $A$ ' in neutral or acidic medium disproportionate to give products ' $\mathrm{B}$ ' and ' $\mathrm{C}$ ' along with water. The sum of spin-only magnetic moment values of $B$ and $C$ is . . . . . .$BM$. (nearest integer)
(Given atomic number of $\mathrm{Mn}$ is $25$ )
Steel differs from pig iron and wrought iron in that it contains