TS EAMCET 4-Aug-2021 Shift 1 Question Paper

(A) If we add ferric chloride over potassium ferrocyanide, it forms a white precipitate that will become blue. The reaction is : $\underset{\text{Ferricchloride}}{4\mathrm{FeCl}_3}+\underset{\text{Potassiumferrocyanide}}{3\mathrm{K}_4[\mathrm{Fe}(\mathrm{CN})_6]}\longrightarrow\underset{\text{White(I) precipitate}}{\mathrm{Fe}_4[\mathrm{Fe}(\mathrm{CN})_6]_3}+\underset{\text{Potassiumchloride}}{3\mathrm{KCl}}$ This is normal reaction because being small quantity of ferric chloride, not all potassium is displaced. (B) Aqueous zinc chloride $(\mathrm{ZnCl}_2)$ reacts with aqueous hydroxide $(\mathrm{NaOH})$ to produce zinc hydroxide $[\mathrm{Zn}(\mathrm{OH})_2]$ and $\mathrm{NaCl}$. Therefore, zinc hydroxide is dissolved when excess $\mathrm{NaOH}$ is added to the precipitate. $\underset{\text{Zinc chloride}}{\mathrm{ZnCl}_2}\xrightarrow{\mathrm{NaOH}}\underset{\text{White ppt.}}{\mathrm{Zn}(\mathrm{OH})_2}\xrightarrow[\mathrm{NaOH}]{\text{ Excess }}\underset{\text{ppt. dissolved(V)}}{\mathrm{Na}_2\mathrm{ZnO}_2}$ (C) Yellow coloured ferric chloride reacts with hydrogen sulphide to form green coloured ferrous chloride. In this reaction, ferric chloride is reduced and $\mathrm{H_2S}$ is oxidised. $\underset{\text{Ferric chloride}}{2\mathrm{FeCl}_3}+\underset{\text{Hydrogensulphide}}{\mathrm{H_2S}}\longrightarrow\underset{\text{Ferrous chloride(green) (II)}}{2\mathrm{FeCl}_2}\underset{\text{Hydrochloric acid}}{2\mathrm{HCl}}+\mathrm{S}$ Hence, correct match is $A \rightarrow 1, B \rightarrow 5, C \rightarrow 2$