Statement I: The order of a reaction is always whole number

Statement II: The molecularity of a reaction is a whole number other than zero, but generally less than 3

Statement I is false but statement II is correct

The correct answer is option 4. Statement I is false, but statement II is correct.

Statement I:  The order of a reaction is always whole number.

This statement is false. The order of a reaction can be a whole number, a fraction, or even zero. The order of a reaction is determined experimentally and represents the relationship between the concentration of reactants and the rate of the reaction.

Statement II: The molecularity of a reaction is a whole number other than zero, but generally less than 3.

This statement is correct. The molecularity of a reaction refers to the number of reactant molecules participating in an elementary step of the reaction. In most cases, elementary reactions involve one or two molecules and are classified as unimolecular (molecularity of 1) or bimolecular (molecularity of 2). Elementary reactions involving three or more molecules are less common but can occur.

Therefore, the correct answer is that Statement I is false, but Statement II is correct.