JEE MAIN - Chemistry (2014 (Offline) - No. 17)

The equation which is balanced and represents the correct product(s) is :
[Mg (H2O)6 ]2+ + (EDTA)4- $$\buildrel {excess\,NaOH} \over \longrightarrow $$ [Mg (EDTA) ]2+ + 6H2O
CuSO4 + KCN $$\to$$ K2 [Cu (CN)4] + K2SO4
Li2O + 2KCl $$\to$$ 2LiCl + K2O
[CoCl(NH3)5]+ + 5H+ $$\to$$ Co2+ + $$5NH_4^+$$ + Cl-

Explanation

(A) [Mg (H2O)6 ]2+ + (EDTA)4- $$\buildrel {excess\,NaOH} \over \longrightarrow $$ [Mg (EDTA) ]2+ + 6H2O

The above equation is incorrect because the product formed would be [Mg (EDTA)]2− .

(B) CuSO4 + KCN $$\to$$ K2[Cu (CN)4] + K2SO4

The above equation is incorrect. Thus, the correct equation is

2KCN + CuSO4 $$\to$$ K2SO4 + Cu + (CN)2(Cyanogen Gas)

(C) Li2O + 2KCl $$\to$$ 2LiCl + K2O

The above equation is incorrect because K2O, a stronger base cannot be generated by a weaker base, Li2O.

(D) [CoCl(NH3)5]+ + 5H+ $$\to$$ Co2+ + $$5NH_4^+$$ + Cl-

The above equation is correct because amine complexes decomposes under acidic medium. Thus, the complex [CoCl(NH3)5] decomposes under acidic conditions to give ammonium ions.

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