(A) If we add ferric chloride over potassium ferrocyanide, it forms a white precipitate that will become blue.
The reaction is :
+| 3K4[Fe(CN)6] |
| Potassium‌ferrocyanide |
⟶| Fe4[Fe(CN)6]3 |
| White(I)‌precipitate |
+ This is normal reaction because being small quantity of ferric chloride, not all potassium is displaced. (B) Aqueous zinc chloride
(ZnCl2) reacts with aqueous hydroxide
(NaOH) to produce zinc hydroxide
[Zn(OH)2] and
NaCl. Therefore, zinc hydroxide is dissolved when excess
NaOH is added to the precipitate.
| NaOH |
| ──────▶ |
| ‌ Excess ‌ |
| ──────▶ |
| NaOH |
(C) Yellow coloured ferric chloride reacts with hydrogen sulphide to form green coloured ferrous chloride.
In this reaction, ferric chloride is reduced and
H2S is oxidised.
+⟶| 2FeCl2 |
| Ferrous‌chloride(green)(II) |
+S Hence, correct match is
A→1,B→5,C→2