A : Rate of reaction depends upon the concentration of the reactants.
R : The order of reaction can be negative with respect to substance present in the reaction.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion , then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion , then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements , then mark (4)

Answer

To analyze the given statements regarding the rate of reaction and the order of reaction, we can break down the solution into clear steps.

### Step 1: Understand the Assertion
The assertion states that "the rate of reaction depends upon the concentration of the reactants."

- In chemical kinetics, the rate of a reaction is often expressed as:
\[ \text{Rate} = k [A]^n \]
where \( k \) is the rate constant, \( [A] \) is the concentration of the reactant, and \( n \) is the order of the reaction with respect to that reactant.

### Step 2: Analyze the Rate Expression
- For most reactions, the rate does depend on the concentration of the reactants. However, there is an exception for zero-order reactions, where the rate is constant and does not depend on the concentration of the reactants.

### Step 3: Conclusion on the Assertion
- Therefore, the assertion is true, but with the caveat that it is not applicable for zero-order reactions.

### Step 4: Understand the Reason
The reason states that "the order of reaction can be negative with respect to the substance present in the reaction."

- To illustrate this, consider a reaction where the rate law can be expressed as:
\[ \text{Rate} = k [A]^m [B]^n \]
where \( m \) and \( n \) can be positive, zero, or negative.

### Step 5: Example of Negative Order
- An example is the reaction of ozone (O3) decomposing in the presence of oxygen (O2). In this case, if we derive the rate law from the rate-determining step, we can find that the order with respect to O2 can be negative.

### Step 6: Conclusion on the Reason
- Thus, the reason is also true, as it is possible for the order of a reaction to be negative with respect to a reactant.

### Step 7: Evaluate the Relationship Between Assertion and Reason
- Although both the assertion and reason are true, the reason does not directly explain the assertion. The assertion is about the dependence of rate on concentration, while the reason discusses the possibility of negative orders.

### Final Conclusion
- The correct option is that both the assertion and reason are true, but the reason is not a correct explanation for the assertion.

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