The reaction of zinc with excess of aqueous alkali, evolves hydrogen gas and gives :

Number of lone pairs of electrons in the central atom of $$\mathrm{SCl}_{2}, \mathrm{O}_{3}, \mathrm{ClF}_{3}$$ and $$\mathrm{SF}_{6}$$, respectively, are :

In following pairs, the one in which both transition metal ions are colourless is :

In neutral or faintly alkaline medium, $$\mathrm{KMnO}_{4}$$ being a powerful oxidant can oxidize, thiosulphate almost quantitatively, to sulphate. In this reaction overall change in oxidation state of manganese will be :