NEET UG 2021 · Chemistry · Question 77
NEET 2021 Chemistry, question 77
Question 77 of the NEET 2021 paper (code O1) is a Chemistry question from Chemical Kinetics. Its idea, Reaction Coordinate Diagrams, was asked only this once in NEET 2017–2026. The NTA final answer key gives option 4.
Updated 2026-10-08
Q77 · Chemistry
For a reaction AB, enthalpy of reaction is −4.2 kJ and enthalpy of activation is 9.6 kJ . The correct potential energy profile for the reaction is shown in option.
The figure, described in words
Four PE vs reaction-progress curves: (1) A and B at the same level; (2) B well above A with only a small hump above B; (3) B higher than A; (4) B lower than A with a hump above A.
- 1[graph: PE vs reaction progress, A and B at the same energy with a hump between]
- 2[graph: PE vs reaction progress, B much higher than A, small dip after the peak to B]
- 3[graph: PE vs reaction progress, B somewhat higher than A, hump between]
- 4[graph: PE vs reaction progress, B lower than A, hump between]Official answer
Official answer: option 4 · NTA final answer key
Same idea
The only question on Reaction Coordinate Diagrams
No other NEET paper from 2017–2026 tested this exact idea.
Reaction Coordinate Diagrams: every question and how it was framed
The chapter
Chemical Kinetics in ten years of NEET
21 questions from 2017–2026, asked in 10 of 10 papers, about 2.0 a paper. Chemical Kinetics alone had 21.