Which of the following reaction in the blast furnace is / are endothermic ?

Options

A. `C(s)+O_(2)(g) hArr CO_(2)(g)`
B. `CO_(2)(g)+C(s) hArr 2CO(g)`
C. `CaCO_(3)(s) hArr CaO(s)+CO_(2)(g)`
D. `Fe_(2)O_(3)(s)+3CO(g) hArr 2Fe(l)+3CO_(2)(g)`

Answer

To determine which reactions in the blast furnace are endothermic, we need to analyze each reaction based on whether they absorb heat or release heat. Endothermic reactions are characterized by the absorption of heat, often involving bond breaking or decomposition processes.

### Step-by-Step Solution:

1. **Identify the Reactions**:
We need to look at the given reactions in the blast furnace. The common reactions include:
- Reaction 1: Carbon + Oxygen → Carbon Dioxide
- Reaction 2: Carbon Dioxide + Carbon → Carbon Monoxide
- Reaction 3: Calcium Carbonate (CaCO3) → Calcium Oxide (CaO) + Carbon Dioxide
- Reaction 4: Iron Oxide + Carbon Monoxide → Iron + Carbon Dioxide

2. **Analyze Each Reaction**:
- **Reaction 1**: Carbon + Oxygen → Carbon Dioxide
- This is a bond formation reaction where heat is released. **(Exothermic)**

- **Reaction 2**: Carbon Dioxide + Carbon → Carbon Monoxide
- This reaction involves breaking the bonds in carbon dioxide, which requires energy input. **(Endothermic)**

- **Reaction 3**: Calcium Carbonate (CaCO3) → Calcium Oxide (CaO) + Carbon Dioxide
- This is a decomposition reaction, which also requires heat to break the bonds in calcium carbonate. **(Endothermic)**

- **Reaction 4**: Iron Oxide + Carbon Monoxide → Iron + Carbon Dioxide
- This reaction releases heat as it forms iron from iron oxide. **(Exothermic)**

3. **Conclusion**:
Based on the analysis:
- Reaction 2 (Carbon Dioxide + Carbon → Carbon Monoxide) is endothermic.
- Reaction 3 (Calcium Carbonate → Calcium Oxide + Carbon Dioxide) is also endothermic.
- Therefore, the endothermic reactions in the blast furnace are Reaction 2 and Reaction 3.

### Final Answer:
The endothermic reactions in the blast furnace are:
- Reaction 2: Carbon Dioxide + Carbon → Carbon Monoxide
- Reaction 3: Calcium Carbonate (CaCO3) → Calcium Oxide (CaO) + Carbon Dioxide

---