Which of the following statements is correct?

Options

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

Answer

To determine which of the given statements about reaction rates is correct, let's analyze each statement step by step.

### Step 1: Analyze Statement 1
**Statement 1:** Rate of reaction decreases with passage of time as concentration of reactant decreases.

- **Explanation:** As a reaction progresses, the concentration of reactants decreases. According to the rate law, the rate of reaction is often dependent on the concentration of reactants. Therefore, as the concentration decreases, the rate of reaction also decreases. This statement is **correct**.

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

- **Explanation:** The rate of reaction is not constant throughout the reaction. It changes as the concentration of reactants changes. Therefore, this statement is **incorrect**.

### Step 3: Analyze Statement 3
**Statement 3:** Rate of reaction is independent of temperature change.

- **Explanation:** The rate of reaction is influenced by temperature. According to the Arrhenius equation, the rate constant (k) increases with an increase in temperature. Therefore, this statement is **incorrect**.

### Step 4: Analyze Statement 4
**Statement 4:** Rate of reaction decreases with increase in concentration of reactant.

- **Explanation:** Generally, the rate of reaction increases with an increase in the concentration of reactants. This statement contradicts the fundamental principles of chemical kinetics. Therefore, this statement is **incorrect**.

### Conclusion
After analyzing all the statements, we find that only **Statement 1** is correct.

### Final Answer
The correct statement is: **1. Rate of reaction decreases with passage of time as concentration of reactant decreases.**

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