Question

Assertion (A): The molecularity of the given reaction is 2. \[ 2\text{HI} \rightarrow \text{H}_2 + \text{I}_2 \] Reason (R): Two molecules of the reactants are involved in simultaneous collision between them. Choose the correct option:

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Molecularity = number of molecules colliding in an elementary step. 1 → Unimolecular 2 → Bimolecular 3 → Termolecular (rare)

Answer 1

The Correct Option is A

The given question involves an assertion about the molecularity of a reaction and a reason that explains it. Let's analyze both the assertion and the reason to determine if they are true and if the reason correctly explains the assertion.

Assertion (A): The molecularity of the given reaction is 2.

The reaction given is:

\(2\text{HI} \rightarrow \text{H}_2 + \text{I}_2\)

Molecularity refers to the number of molecules that come together to react in an elementary step. In this reaction, two molecules of hydrogen iodide (HI) are involved in the reaction process. Therefore, the molecularity is 2, which makes the assertion true.

Reason (R): Two molecules of the reactants are involved in simultaneous collision between them.

Molecularity indeed involves the simultaneous collision of the specified number of reactant molecules in a chemical reaction. Since both reactants are required to collide at the same time to proceed with the reaction, this reason is true and aligns with the definition of molecularity.

Now, let's examine the given options:

• Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• Assertion (A) is true, but Reason (R) is false.
• Assertion (A) is false, but Reason (R) is true.

Since both the assertion and the reason are correct, and the reason provides an accurate explanation of why the molecularity is 2, the first option is the correct choice.

Conclusion: Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).