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Friday, 9 October

JEE Main 2025 · ChemistryMultiple choiceDiagram basedMediumData or graph

JEE Main 7 April 2025, Shift 1, Chemistry Q57

Question 57 of 75 in this shift, Chemistry question 7 of 25, Section A.

A person's wound was exposed to some bacteria and then bacterial growth started to happen at the same place. The wound was later treated with some antibacterial medicine and the rate of bacterial decay(r) was found to be proportional with the square of the existing number of bacteria at any instance. Which of the following set of graphs correctly represents the 'before' and 'after' situation of the application of the medicine? [Given: N = No. of bacteria, t = time, bacterial growth follows 1st1^{\mathrm{st}} order kinetics.]

The figure, in words

Each option is a pair of graphs labelled Before (N/N0 versus t, with ticks 1 and 2 on the N/N0 axis) and After (r versus N).
  1. (1)[figure: Before: N/N0 vs t, exponential rise starting at 1; After: r vs N, decreasing convex curve]
  2. (2)[figure: Before: N/N0 vs t, exponential rise starting at 1; After: r vs N, straight line through origin]
  3. (3)[figure: Before: N/N0 vs t, exponential rise starting near 0 (axis break below 1); After: r vs N, concave-up curve through origin]
  4. (4)[figure: Before: N/N0 vs t, exponential rise starting at 1; After: r vs N, concave-up curve through origin]Official answer

Official answer

Option 4

NTA final key.

Chapter
Chemical Kinetics
Topic
Rate Laws
Idea tested
Rate vs Concentration Graphs

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.