See image — AITS & Test Series Chemistry Question

💡 Solution & Explanation

CoCl2 + H2S  CoS  + 2HCl 3CoS + 6HCl + 2HNO3  3CoCl2 + 2NO + 3S + 4H2O aqua regia KNO2 + CH3COOH  CH3COOK + HNO2 CoCl2 + 2KNO2  Co(NO2)2 + 2KCl Co(NO2)2 + 2HNO2  Co(NO2)3 + NO + H2O Co(NO2)3 + 3KNO2  K3[Co(NO2)6] Oxidation number of cobalt in this compound is +3. AITS-CRT-I (Paper-1)-PCM (Sol.)-JEE(Advanced)/18 FIITJEE Ltd., FIITJEE House, 29-A, Kalu Sarai, Sarvapriya Vihar, New Delhi -110016, Ph 46106000, 26569493, Fax 26513942 website: www.fiitjee.com 8