which one of the following statements for the order of a reaction is incorrect ?

Options

A. order is not influenced by stoichiometric coefficient of the reactants
B. Order of reaction is sum of power to the concentration terms of reactants to express the rate of reaction
C. Order of reaction is always whole number
D. Order can be determined only experimentally

Explanation

To determine which statement regarding the order of a reaction is incorrect, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Order of Reaction**:
- The order of a reaction is defined as the sum of the powers of the concentration terms of the reactants in the rate law expression. It can be determined experimentally.

2. **Analyzing Option 1**:
- **Statement**: "Order is not influenced by stoichiometric coefficient of reactants."
- **Analysis**: This statement is correct. The order of a reaction is determined by the rate law and not directly by the stoichiometric coefficients.

3. **Analyzing Option 2**:
- **Statement**: "Order of reaction is the sum of power to the concentration terms of reactants to express the rate of reaction."
- **Analysis**: This statement is also correct. The order is indeed the sum of the exponents in the rate law.

4. **Analyzing Option 3**:
- **Statement**: "The order of reaction is a whole number."
- **Analysis**: This statement is incorrect. The order of a reaction can be a fraction, zero, or a whole number. It is not restricted to whole numbers only.

5. **Analyzing Option 4**:
- **Statement**: "Order can be determined only experimentally."
- **Analysis**: This statement is correct. The order of a reaction must be determined through experimental data, as it cannot be deduced solely from the stoichiometry of the reaction.

### Conclusion:
Based on the analysis, the incorrect statement regarding the order of a reaction is:
- **"The order of reaction is a whole number."**