Identify the correct statement:
Show Hint
- Molecularity of a reaction is an experimental quantity.
- For complex reactions molecularity has no meaning.
- Molecularity of a reaction can be zero or even a fraction.
- Molecularity more than three is very common in chemical reactions.
The Correct Option is B
Solution and Explanation
Molecularity is defined theoretically as the number of reacting species (atoms, ions, or molecules) taking part in an elementary reaction, which must collide simultaneously.
Step 2: Meaning
Since complex reactions proceed via multiple elementary steps, there is no single simultaneous collision involving all reactants.
Step 3: Analysis
Option (A) is incorrect because order is experimental, while molecularity is theoretical.
Option (C) is incorrect because molecularity must be a whole number (at least 1).
Option (D) is incorrect because simultaneous collisions of more than three molecules are statistically highly improbable.
Option (B) is mathematically and theoretically correct because molecularity is only defined for individual elementary steps, not the overall complex reaction.
Step 4: Conclusion
The statement regarding the lack of meaning of molecularity for complex reactions is the only correct one.
Final Answer: (B)
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Top CBSE CLASS XII Molecularity Questions
Why is molecularity applicable only for elementary reactions whereas order is applicable for elementary as well as complex reactions?
- Write any two differences between the order of a reaction and molecularity of a reaction.
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$2HI \longrightarrow H_2 + I_2$
Reason (R): Two molecules of the reactants are involved in simultaneous collision between them. - Identify the correct statement :
- Assertion (A) : The molecularity of the given reaction is 2.
\( 2\text{HI} \longrightarrow \text{H}_2 + \text{I}_2 \)
Reason (R) : Two molecules of the reactants are involved in simultaneous collision between them.
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