- An aqueous solution of a compound A is acidic towards litmus and A sublimes at about

CHEMISTRY · Single correct · ISC · Chemistry · Coordination Compounds · Equilibrium

Problem

- An aqueous solution of a compound A is acidic towards litmus and A sublimes at about 300∘C300^\circ\text{C} . - A solution of A, on treatment with an excess of NH4SCN\text{NH}_4\text{SCN} , gives a red compound B, and on treatment with a solution of K4[Fe(CN)6]\text{K}_4[\text{Fe}(\text{CN})_6] , gives a blue compound C. - The solid A, on being heated with an excess of K2Cr2O7\text{K}_2\text{Cr}_2\text{O}_7 in the presence of concentrated H2SO4\text{H}_2\text{SO}_4 , evolves deep red vapours of D. - On passing the vapours of D into a solution of NaOH\text{NaOH} and then adding the solutions of acetic acid and lead acetate, a yellow precipitate of a compound E is obtained. - Which of the following can be the composition of B and C respectively? (1) Ni(SCN)2\text{Ni}(\text{SCN})_2 and Ni2[Fe(CN)6]\text{Ni}_2[\text{Fe}(\text{CN})_6] (2) Co(SCN)2\text{Co}(\text{SCN})_2 and Co2[Fe(CN)6]\text{Co}_2[\text{Fe}(\text{CN})_6] (3) [Fe(SCN)6]3−[\text{Fe}(\text{SCN})_6]^{3-} and Fe3[Fe(CN)6]2\text{Fe}_3[\text{Fe}(\text{CN})_6]_2 (4) Fe(SCN)3\text{Fe}(\text{SCN})_3 and Fe4[Fe(CN)6]3\text{Fe}_4[\text{Fe}(\text{CN})_6]_3

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