Question

Which of the following properties are common to the elements manganese, iron, cobalt, nickel and copper?

(I) Coloured ions in aqueous solution
(II) Oxides of nitrogen on reaction with concentrated $H{NO}_3$
(III) Chlorides of formula $M{Cl}_2$ and $M{Cl}_3$

• A. I, II, III
• B. I, II
• C. II, III
• D. I only

Answer 1

The correct option is D I only

Manganese, iron, cobalt, nickel and copper easily form coloured ions in the solution due to presence of unpaired electrons in the outer electronic configuration.
For example, manganese with outer electronic configuration of $3d^{5}4s^2$ forms $M{n}^{2+}$ ion with outer electronic configuration of $3d^{5}4s^0$ . It contains five unpaired electrons and is coloured.