Consider the reaction `A to B`. The concentration of both the reactants and the products varies exponentially with time. Which of the following figure correctly describes the change in concentration of reactants and products with time ?

Options

A.
B.
C.
D.

Explanation

To solve the question regarding the reaction `A to B` and the change in concentration of reactants and products over time, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Reaction**:
The reaction is represented as `A → B`, where `A` is the reactant and `B` is the product. As the reaction proceeds, `A` is converted into `B`.

2. **Concentration Changes**:
- Initially, the concentration of reactant `A` is at its maximum.
- As the reaction progresses, the concentration of `A` decreases while the concentration of `B` increases.

3. **Graphical Representation**:
- The x-axis represents time, while the y-axis represents concentration.
- The concentration of reactant `A` will show a decreasing exponential trend as the reaction proceeds.
- Conversely, the concentration of product `B` will show an increasing exponential trend.

4. **Rate of Reaction**:
- The rate of reaction is directly proportional to the concentration of the reactant. Therefore, as the concentration of `A` decreases, the rate of reaction also decreases.
- This means that the slope of the graph for `A` will become less steep over time.

5. **Identifying the Correct Graph**:
- We need to look for a graph where:
- The concentration of `A` starts high and decreases over time.
- The concentration of `B` starts low and increases over time.
- The correct graph will depict these trends accurately.

6. **Conclusion**:
- After analyzing the provided graphs, we determine that Graph B correctly represents the change in concentration of reactants and products with time.