Which plot represents for an exothermic reaction ?

Options

A.
B.
C.
D.

Explanation

To determine which plot represents an exothermic reaction, we need to understand the characteristics of exothermic reactions in terms of energy changes.

### Step-by-Step Solution:

1. **Definition of Exothermic Reaction**:
- An exothermic reaction is one in which the products have lower energy than the reactants. This means that energy is released during the reaction.

2. **Understanding Energy Levels**:
- In an energy diagram, the vertical axis represents the energy of the reactants and products, while the horizontal axis represents the progress of the reaction (often time).
- For an exothermic reaction, the energy level of the products must be lower than that of the reactants.

3. **Energy Change Calculation**:
- The change in enthalpy (ΔH) for an exothermic reaction is negative. This can be expressed as:
\[ \Delta H = \text{Energy of Products} - \text{Energy of Reactants} < 0 \]
- This indicates that the energy of the products is less than the energy of the reactants.

4. **Analyzing the Plots**:
- **Plot A**: If the energy of the reactants is higher than that of the products, this plot represents an exothermic reaction.
- **Plot B**: If the energy of the reactants is lower than that of the products, this represents an endothermic reaction.
- **Plot C**: If the energy levels of reactants and products are the same, this indicates no reaction or a reaction that doesn't involve energy change.
- **Plot D**: Similar to Plot C, if the energy levels are the same, it also indicates no net energy change.

5. **Conclusion**:
- Among the given options, **Plot A** is the only plot that shows the energy of the products being less than that of the reactants, confirming it as the representation of an exothermic reaction.

### Final Answer:
The plot that represents an exothermic reaction is **Plot A**.