Properties common to the elements manganese, iron, cobalt, nickel and copper include the ready formation by them all of
(I) coloured ions in aqueous solution
(II) oxides of nitrogen are formed o

Question

Properties common to the elements manganese, iron, cobalt, nickel and copper include the ready formation by them all of
(I) coloured ions in aqueous solution
(II) oxides of nitrogen are formed on reaction with concentrated HNO3
(III) chlorides of formula MCl2 and MCl3

Prashant Kotian · Accepted Answer

Correct answer: B. Step 1: All these elements (Mn, Fe, Co, Ni, Cu) are transition metals that form colored hydrated ions in aqueous solution due to d-d electronic transitions, so Statement I is correct. Step 2: Reaction of these metals with concentrated nitric acid (HNO3) results in the reduction of nitric acid, liberating oxides of nitrogen (predominantly NO2 gas), so Statement II is correct. Step 3: While all of them form divalent chlorides (MCl2), copper does not form a stable trivalent chloride (CuCl3 is highly unstable/non-existent), and nickel(III) chloride is also highly unstable. Thus, Statement III is incorrect. Therefore, the correct option is (b).

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