Concept:Activation energy (\( E_a \)) is primarily determined by the inherent chemical bonds that must be broken in the reactants.
Solution:- The nature of the reactants (the strength and type of their chemical bonds) is the primary determinant of the activation energy barrier.
- Note on exact exam key: While standard physical chemistry states that \( E_a \) is fundamentally independent of temperature, the specific local examining body (ETEA) marked 'Both A and B' (Temperature and Nature) as the correct answer in their official key, likely conflating effective kinetic energy distribution with the barrier itself. We retain the historical key for accuracy.
Why other options are incorrect:Strictly speaking, only the nature of the reactant and presence of a catalyst define \( E_a \). However, one must follow the historical exam key provided.
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Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.