MCQ
The potassium ferrocyanide solution gives Prussian blue colour, when added to :
  • A
    $\mathrm{CoCl}_{3}$
  • B
    $\mathrm{FeCl}_{2}$
  • C
    $\mathrm{CoCl}_{2}$
  • $\mathrm{FeCl}_{3}$

Answer

Correct option: D.
$\mathrm{FeCl}_{3}$
d
$\left.\mathrm{FeCl}_{3}+\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right] \rightarrow \mathrm{Fe}_{4}[\mathrm{Fe}(\mathrm{CN})]_{6}\right]_{3}$

$\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad$Prussian blue

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$1.$ Among the following, identify the correct statement.

$(A)$ Chloride ion is oxidized by $\mathrm{O}_2$

$(B)$ $\mathrm{Fe}^{2+}$ is oxidized by iodine

$(C)$ Iodide ion is oxidized by chlorine

$(D)$ $\mathrm{Mn}^{2+}$ is oxidized by chlorine

$2.$ While $\mathrm{Fe}^{3+}$ is stable, $\mathrm{Mn}^{3+}$ is not stable in acid solution because

$(A)$ $\mathrm{O}_2$ oxidises $\mathrm{Mn}^{2+}$ to $\mathrm{Mn}^{3+}$

$(B)$ $\mathrm{O}_2$ oxidises both $\mathrm{Mn}^{2+}$ and $\mathrm{Fe}^{2+}$ to $\mathrm{Fe}^{3+}$

$(C)$ $\mathrm{Fe}^{3+}$ oxidizes $\mathrm{H}_2 \mathrm{O}$ to $\mathrm{O}_2$

$(D)$ $\mathrm{Mn}^{3+}$ oxidises $\mathrm{H}_2 \mathrm{O}$ to $\mathrm{O}_2$

$3.$ Sodium fusion extract, obtained from aniline, on treatment with iron $(II)$ sulphate and $\mathrm{H}_2 \mathrm{SO}_4$ in presence of air gives a Prussian blue precipitate. The blue colour is due to the formation of

$(A)$ $\mathrm{Fe}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]_3$ $(B)$ $\mathrm{Fe}_3\left[\mathrm{Fe}(\mathrm{CN})_6\right]_2$

$(C)$ $\mathrm{Fe}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]_2$ $(D)$ $\mathrm{Fe}_3\left[\mathrm{Fe}(\mathrm{CN})_6\right]_3$

Give the answer question $1,2$ and $3.$

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