Q19 / 75 · JEE Main 2026 (04 April Shift 2) · Chemistry
Among $Fe^{3+}$, $Pb^{2+}$, $Cu^{2+}$ and $Mn^{2+}$, identify the one that gets precipitated out while passing $H_2S$ in presence of $NH_4OH$ as group reagent. The highest possible oxidation state of the corresponding metal is
- A$+3$
- B$+4$
- C$+2$
- Correct answerD$+7$
Solution
The group reagent $H_2S$ in the presence of $NH_4OH$ is used for the precipitation of Group IV cations in qualitative analysis.
Among the given ions, $Mn^{2+}$ belongs to Group IV and is precipitated as $MnS$.
$Pb^{2+}$ and $Cu^{2+}$ belong to Group II and are precipitated by $H_2S$ in an acidic medium.
$Fe^{3+}$ belongs to Group III and is precipitated as $Fe(OH)_3$ by $NH_4OH$ in the presence of $NH_4Cl$.
The metal corresponding to the precipitated ion is Manganese ($Mn$).
The electronic configuration of $Mn$ is $[Ar] 3d^5 4s^2$. By losing all its valence electrons, it can exhibit a maximum oxidation state of $+7$ (for example, in $KMnO_4$).
Answer: $+7$
Among the given ions, $Mn^{2+}$ belongs to Group IV and is precipitated as $MnS$.
$Pb^{2+}$ and $Cu^{2+}$ belong to Group II and are precipitated by $H_2S$ in an acidic medium.
$Fe^{3+}$ belongs to Group III and is precipitated as $Fe(OH)_3$ by $NH_4OH$ in the presence of $NH_4Cl$.
The metal corresponding to the precipitated ion is Manganese ($Mn$).
The electronic configuration of $Mn$ is $[Ar] 3d^5 4s^2$. By losing all its valence electrons, it can exhibit a maximum oxidation state of $+7$ (for example, in $KMnO_4$).
Answer: $+7$
Hence, the correct answer is option: 'D'.