Statement I: Formation of HI is a bimolecular reaction

Statement II: Two molecules of reactants are involved in this reaction

Statement I and statement II are correct and statement II is the correct explanation of statement I

The statement that the formation of HI is a bimolecular reaction is true. This is because two molecules of reactants are involved in this reaction. The reactants are hydrogen gas (H2) and iodine gas (I2). The reaction can be written as follows:

\[H_2   +   I_2 \rightarrow 2HI\]

In this reaction, one molecule of hydrogen gas reacts with one molecule of iodine gas to form two molecules of hydrogen iodide. Therefore, two molecules of reactants are involved in this reaction.

The statement that the order of reaction is 2 is false. The order of reaction is the sum of the exponents of the concentrations of the reactants in the rate expression. In this case, the rate expression is

\[rate = k[H_2][I_2]\]

The order of reaction is 2 because the exponent of \([H_2]\) is 1 and the exponent of \([I_2]\) is 1.

Therefore,

\(\text{Order of reaction  = } 1 + 1 = 2\)