The rate of a chemical reaction is increased in presence of a catalyst. This is because 

Options

A. activation energy of the reaction is less in the new path
B. heat of reacton is decreased
C. threshold energy is increased
D. activation energy of the new path is more

Answer

To solve the question regarding why the rate of a chemical reaction is increased in the presence of a catalyst, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Catalysts**: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It achieves this by providing an alternative reaction pathway.

2. **Activation Energy**: Every chemical reaction requires a certain amount of energy to proceed, known as the activation energy (Ea). This energy is needed to break bonds in the reactants so that new bonds can form in the products.

3. **Effect of Catalysts on Activation Energy**: When a catalyst is present, it lowers the activation energy required for the reaction. This means that more reactant molecules can have enough energy to overcome this barrier at a given temperature.

4. **Increased Reaction Rate**: With the lower activation energy provided by the catalyst, the number of effective collisions between reactant molecules increases. This leads to a higher rate of reaction, allowing the reaction to proceed faster.

5. **Direction of Reaction**: Importantly, catalysts affect both the forward and reverse reactions equally, meaning they do not alter the position of equilibrium but only help achieve it faster.

6. **Conclusion**: Therefore, the correct reason for the increase in the rate of a chemical reaction in the presence of a catalyst is that it provides an alternative pathway with a lower activation energy.

### Final Answer:
The rate of a chemical reaction is increased in the presence of a catalyst because it provides an alternative pathway for the reaction to proceed with lower activation energy.

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