In which of the following reaction boron does not act as reducing agent ?

Options

A. `B + CO_(2) to`
B. `B + Mg to `
C. `B + SiO_(2) to`
D. `B + HNO_(3) to`

Answer

To determine in which reaction boron does not act as a reducing agent, we need to analyze each option provided. A reducing agent is a substance that donates electrons to another substance, thereby reducing that substance while being oxidized itself. Conversely, an oxidizing agent gains electrons and is reduced.

Let's go through the options step by step:

### Step 1: Analyze Option A - B + CO2
- In this reaction, boron (B) reacts with carbon dioxide (CO2).
- The oxidation state of carbon in CO2 is +4.
- Since carbon can be reduced (from +4 to a lower oxidation state), CO2 acts as an oxidizing agent.
- Therefore, boron acts as a reducing agent in this reaction.
- **Conclusion:** Boron acts as a reducing agent here.

### Step 2: Analyze Option B - B + Mg
- In this reaction, boron reacts with magnesium (Mg).
- Magnesium is a metal and typically does not act as an oxidizing agent; metals are generally reducing agents.
- Since magnesium cannot oxidize itself, boron cannot act as a reducing agent in this case.
- **Conclusion:** Boron does not act as a reducing agent here.

### Step 3: Analyze Option C - B + SiO2
- In this reaction, boron reacts with silicon dioxide (SiO2).
- The oxidation state of silicon in SiO2 is +4, which is its highest oxidation state.
- Since SiO2 can act as an oxidizing agent, boron can act as a reducing agent.
- **Conclusion:** Boron acts as a reducing agent here.

### Step 4: Analyze Option D - B + HNO3
- In this reaction, boron reacts with nitric acid (HNO3).
- The oxidation state of nitrogen in HNO3 is +5, which is also the highest oxidation state for nitrogen.
- Hence, HNO3 acts as an oxidizing agent, allowing boron to act as a reducing agent.
- **Conclusion:** Boron acts as a reducing agent here.

### Final Answer:
Boron does not act as a reducing agent in option **B (B + Mg)**.

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