alleryStart learning →What does the molecularity of an elementary reaction count?
AThe number of reactant species taking part
BThe number of steps in the whole mechanism
CThe number of products the step gives out
DThe number of catalyst molecules involved
Answer & Solution
Correct answer: A. The number of reactant species taking part
1. Molecularity is a property of a single elementary step, not of a whole reaction.
2. It counts the reactant species, whether atoms, molecules or ions, that come together in that step.
3. One species makes the step unimolecular, two make it bimolecular and three make it termolecular.
4. Products are not counted, so a step giving two products is not automatically bimolecular.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.6 Reaction Mechanisms_
Keep practising Kinetics
Browse all Kinetics questions for IMU CET, or explore more Chemistry topics.
Related questions
Which enzyme deficiency is described as the most common one in humans?Why are most catalytic converters preheated by an electric heater?Which catalyst coats the surface of most modern three way catalytic converters?Which international treaty began phasing out chemicals linked to ozone destruction?Which prize did Paul Crutzen, Mario Molina and Sherwood Rowland share for their work on ozNitric oxide takes part in the decomposition of ozone. Why is it called a catalyst?On a reaction diagram the reagents sit at 6 kJ and the transition state at 20 kJ. What is What effect does a catalyst have on the position of an equilibrium?