Which of the following statement is correct ?

Options

A. There rate of a reaction decreases with passage of time as the concentration of reactants decreases.
B. The rate of a reaction is same at any time during the reaction.
C. The rate of a reaction is independent of temperature change.
D. The rate of a reaction decreases with increase in concentration of reactant(s).

Explanation

To determine which statement is correct regarding the rate of reaction, let's analyze each option step by step.

### Step 1: Analyze Option 1
**Statement:** The rate of reaction decreases with the passage of time as the concentration of reactant decreases.

- **Explanation:** As a reaction proceeds, the reactants are consumed, leading to a decrease in their concentration. Since the rate of reaction is often dependent on the concentration of reactants, as the concentration decreases, the rate of reaction also decreases. This statement is correct.

### Step 2: Analyze Option 2
**Statement:** The rate of reaction is the same at any time during the reaction.

- **Explanation:** This statement is incorrect because the rate of reaction changes over time as the concentration of reactants decreases. Therefore, the rate cannot remain constant throughout the reaction.

### Step 3: Analyze Option 3
**Statement:** The rate of reaction is independent of temperature.

- **Explanation:** This statement is also incorrect. The rate of reaction is dependent on temperature; typically, as temperature increases, the rate of reaction increases due to higher kinetic energy of the molecules, which leads to more frequent and effective collisions.

### Step 4: Analyze Option 4
**Statement:** The rate of reaction decreases with an increase in concentration of reactant.

- **Explanation:** This statement is incorrect. Generally, increasing the concentration of reactants leads to an increase in the rate of reaction, as there are more molecules available to collide and react.

### Conclusion
After analyzing all the options, we find that **Option 1** is the correct statement: "The rate of reaction decreases with the passage of time as the concentration of reactant decreases."

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