Question

The correct option(s) to distinguish nitrate salts of $Mn^{2+}$ and $Cu^{2+}$ taken separately is (are)

• A. $Mn^{2+}$ shows the characteristic green colour in the flame test
• B. Only $Cu^{2+}$ shows the formation of precipitate by passing $H_2S$ in acidic medium
• C. Only $Mn^{2+}$ shows the formation of precipitate by passing $H_2S$ in faintly basic medium
• D. $Cu^{2+} /Cu$ has higher reduction potential than $Mn^{2+} /Mn$ (measured under similar conditions)

Answer 1

Answer: (B), (D)

(A) $Cu^{+2}$ and $Mn^{+2}$ both gives green colour in flame test and cannot distinguished.
(B) $Cu^{+2}$ belongs to group-II of cationic radical will gives ppt. of CuS in acidic medium.
(C) $Cu^{+2}$ and $Mn^{+2}$ both form ppt. in basic medium.
(D) $Cu^{+2} /Cu = +0.34 \, V \, (SRP)$
$Mn^{+2} /Mn = - 1.18 \, V \, (SRP)$