Question

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

• A. $M{n}^{2+}$ shows the characteristic green colour in the flame test.
• B. Only $C{u}^{2+}$ shows the formation of precipitate by passing $H_{2}S$ in acidic medium.
• C. Only $M{n}^{2+}$ shows the formation of precipitate by passing $H_{2}S$ in faintly basic medium.
• D. $C{u}^{2+}/Cu$ has higher reduction potential than $M{n}^{2+}/Mn$ (measured under similar conditions).

Answer 1

Answer: (B), (D)

The correct options are
B Only $C{u}^{2+}$ shows the formation of precipitate by passing $H_{2}S$ in acidic medium.
D $C{u}^{2+}/Cu$ has higher reduction potential than $M{n}^{2+}/Mn$ (measured under similar conditions).

(A) $C{u}^{2+}$ and $M{n}^{2+}$ both give green colour in a flame test, thus cannot be distinguished.

(B) $C{u}^{2+}$ belongs to group-II of cationic radical will give ppt. of $CuS$ in acidic medium.

(C) $C{u}^{2+}$ and $M{n}^{2+}$ both form ppt. in basic medium.

(D) $C{u}^{2+}/Cu=+0.34V\left(SRP\right)$ and $M{n}^{2+}/Mn=-1.18V\left(SRP\right)$.