Question

The correct option(s) to distinguish nitrate salts of $M{n}^{2+}$ and $C{u}^{2+}$ taken separately is (are)

(1) $M{n}^{2+}$ shows the characteristic green colour in the flame test

(2) only $C{u}^{2+}$ shows the formation of precipitate by passing $H_{2}S$ in acidic medium

(3) only $M{n}^{2+}$ shows the formation of precipitate by passing $H_{2}S$ in faintly basic medium

(4) ${\text{Cu}}^{2+}|\text{Cu}$ has higher reduction potential than ${\text{Mn}}^{2+}|\text{Mn}$ (measured under similar conditions)

• A. 1, 2
• B. 1, 3
• C. 2, 4
• D. 1, 2, 4

Answer 1

Answer: (C)

$\left(A\right)$ Manganese show pale purple colour in flame test.

$\left(B\right)$ $C{u}^{2+}\stackrel{H_{2}SHCl}{\to }\underset{\text{Black ppt.}}{CuS\downarrow }$

$\left(C\right)$ Both $C{u}^{2+}$ and $M{n}^{2+}$ form precipitate with $H_{2}S$ in basic medium.

$\left(\text{D}\right){\text{E}}_{{\left(\text{Cu}\right)}^{2+}|\text{Cu}}^{\text{o}}=+0.34\text{V},{\text{E}}_{{\left(\text{Mn}\right)}^{2+}|\text{Mn}}^{\text{o}}=-1.18\text{V}$