Which of the following is an example of a trimolecular (termolecular) reaction?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( \ce{2NO + O2 -> 2NO2} \)
The molecularity of an elementary reaction is the number of reacting species that must collide at the same time. In \( \ce{2NO + O2 -> 2NO2} \), two molecules of NO and one molecule of O2 collide together, so three species take part: the reaction is trimolecular.
NCERT (2026-27 edition):
3.2.4 Molecularity of a Reaction – “Trimolecular or termolecular reactions involve simultaneous collision between three reacting species, for example, 2NO + O2 → 2NO2”