Activation Energy and Reaction Types — NEET Biology
📚 Practice ConceptThe y-axis represents the potential energy content. The x-axis represents the progression of the structural transformation or states through the 'transition state'. You would notice two things. The energy level difference between S and P. If 'P' is at a lower level than 'S', the reaction is an exothermic reaction. One need not supply energy (by heating) in order to form the product. However, whether it is an exothermic or spontaneous reaction or an endothermic or energy requiring reaction, the 'S' has to go through a much higher energy state or transition state. The difference in average energy content of 'S' from that of this transition state is called 'activation energy'.
Assertion (A): All chemical reactions require activation energy to proceed regardless of their energy balance. Reason (R): Both exothermic and endothermic reactions need energy input to reach the transition state.
View solution & NCERT explanation
Correct answer: A — If both assertion and reason are true and the reason is the correct explanation of the assertion.
Both statements are true from NCERT. The Assertion describes the universal need for activation energy. The Reason explains WHY - NCERT states “However, whether it is an exothermic or spontaneous reaction or an endothermic or energy requiring reaction, the ‘S’ has to go through a much higher energy state.” This explains that activation energy is separate from overall energy change.
What does NCERT say about y-axis represents potential energy?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.