`H_(2)O_(2)` is commonly ·prepared in laboratory by the reaction of

Options

A. `PbO_(2)+H_(2)SO_(4)`
B. `MnO_(2)+H_(2)SO_(4)`
C. `BaO_(2)+H_(2)O+CO_(2)`
D. `Na_(2)O_(2)+H_(2)O`

Answer

To determine how hydrogen peroxide (H₂O₂) is commonly prepared in the laboratory, we will analyze the given options step by step.

### Step 1: Analyze the First Option
**Reaction:** PbO₂ + H₂SO₄
**Products:** PbSO₄ + O₂ + H₂O

When lead dioxide (PbO₂) reacts with sulfuric acid (H₂SO₄), it produces lead sulfate (PbSO₄), oxygen gas (O₂), and water (H₂O).
**Balanced Reaction:**
2 PbO₂ + 2 H₂SO₄ → 2 PbSO₄ + O₂ + 2 H₂O

**Conclusion:** This reaction does not produce H₂O₂, so this option is incorrect.

### Step 2: Analyze the Second Option
**Reaction:** MnO₂ + H₂SO₄
**Products:** MnSO₄ + O₂ + H₂O

When manganese dioxide (MnO₂) reacts with sulfuric acid (H₂SO₄), it forms manganese sulfate (MnSO₄), oxygen gas (O₂), and water (H₂O).
**Balanced Reaction:**
2 MnO₂ + 2 H₂SO₄ → 2 MnSO₄ + O₂ + 2 H₂O

**Conclusion:** This reaction also does not yield H₂O₂, so this option is incorrect.

### Step 3: Analyze the Third Option
**Reaction:** BaO₂ + H₂O + CO₂
**Products:** BaCO₃ + H₂O₂

In this reaction, barium peroxide (BaO₂) reacts with water (H₂O) and carbon dioxide (CO₂). The products are barium carbonate (BaCO₃) and hydrogen peroxide (H₂O₂).
**Balanced Reaction:**
BaO₂ + H₂O + CO₂ → BaCO₃ + H₂O₂

**Conclusion:** This reaction produces H₂O₂, making this option correct.

### Step 4: Analyze the Fourth Option
**Reaction:** Na₂O₂ + H₂O
**Products:** NaOH + O₂

When sodium peroxide (Na₂O₂) reacts with water (H₂O), it produces sodium hydroxide (NaOH) and oxygen gas (O₂).
**Balanced Reaction:**
2 Na₂O₂ + 2 H₂O → 4 NaOH + O₂

**Conclusion:** This reaction does not produce H₂O₂, so this option is incorrect.

### Final Conclusion
After analyzing all the options, the correct method for preparing hydrogen peroxide (H₂O₂) in the laboratory is through the reaction of barium peroxide (BaO₂) with water and carbon dioxide, which is option 3.