Question

In a basic medium, H₂O₂ exhibits which of the following reactions?

A. Mn²⁺ → Mn⁴⁺

B. I₂ → I^–

C. PbS → PbSO₄

• A. (A), (C) only
• B. (A) only
• C. (B) only
• D. (A), (B) only

Answer 1

The correct option is D

(A), (B) only

Explanation for correct answer:-

Option (D): (A), (B) only:

Reaction of ${\mathbf{H}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{2}}$with Manganese(basic medium):-

• In the basic medium ${\mathrm{H}}_2{\mathrm{O}}_2$(Hydrogen peroxide) acts as the oxidising agent.
• ${\mathrm{H}}_2{\mathrm{O}}_2$oxidises the Manganese from $+2$ to $+4$ state.
• The complete reaction:

${\mathrm{Mn}}^{2+}+{\mathrm{H}}_2{\mathrm{O}}_2\to {\mathrm{Mn}}^{+4}+2{\mathrm{OH}}^{-}$

Reaction of ${\mathbf{H}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{2}}$with Iodine (basic medium):-

• In the basic medium ${\mathrm{H}}_2{\mathrm{O}}_2$(Hydrogen peroxide) acts as the reducing agent.
• ${\mathrm{H}}_2{\mathrm{O}}_2$ reduces the Iodine from $0$to $-1$state.
• The complete reaction:

${\mathrm{I}}_2+{\mathrm{H}}_2{\mathrm{O}}_2+2{\mathrm{OH}}^{-}\to 2{\mathrm{I}}^{-}+2{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$

Explanation for incorrect answer:-

Option (A): (A), (C) only:

Reaction of ${\mathbf{H}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{2}}$with Manganese(basic medium):-

• In the basic medium ${\mathrm{H}}_2{\mathrm{O}}_2$(Hydrogen peroxide) acts as the oxidising agent.
• ${\mathrm{H}}_2{\mathrm{O}}_2$oxidises the Manganese from $+2$to $+4$state.
• The complete reaction:

${\mathrm{Mn}}^{2+}+{\mathrm{H}}_2{\mathrm{O}}_2\to {\mathrm{Mn}}^{+4}+2{\mathrm{OH}}^{-}$

Reaction of ${\mathbf{H}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{2}}$with Lead sulphide (acidic medium):-

• ${\mathrm{H}}_2{\mathrm{O}}_2$(Hydrogen peroxide) acts as the oxidising agent but acts like so only in the acidic medium not basic.
• ${\mathrm{H}}_2{\mathrm{O}}_2$oxidises the Sulphur from $+2$to $+6$ state.
• The complete reaction:

$\underset{\mathrm{Lead}\mathrm{sulphide}}{\mathrm{PbS}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}\mathrm{peroxide}}{4{\mathrm{H}}_2{\mathrm{O}}_2\left(\mathrm{aq}\right)}\to \underset{\mathrm{Lead}\mathrm{sulphate}}{{\mathrm{PbSO}}_4\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

• Thus Hydrogen peroxide does not exhibit in the reaction with Lead sulphide in basic medium.
• It reacts with Lead sulphide in acidic medium only.
• Hence it is the incorrect option

Option (B): (A) only:

• Both reactions (A) and (B) are exhibited by Hydrogen peroxide, not just (A).
• Hence it is the incorrect option.

Option (C): (B) only:

• Both reactions (A) and (B) are exhibited by Hydrogen peroxide, not just (B).
• Hence it is the incorrect option.

Therefore, option (D) (A), (B) only is the correct answer