MCQMediumJEE Main 2025 · 7 April, Shift 1Order & Molecularity

Chemistry Question from JEE Main 2025 · 7 April, Shift 1

A person's wound was exposed to some bacteria and then bacteria growth started to happen at the same place. The wound was later treated with some antibacterial medicine and the rate of bacterial decay (rr) 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: NN = No. of bacteria, tt = time, bacterial growth follows 11st order kinetics.]

Four options of paired graphs labeled Before and After, comparing bacterial growth versus time and decay rate versus number of bacteria.
  • A

    (1) Before: NN0\frac{N}{N_0} rises exponentially from 11 as tt increases. After: rr starts high and falls off as NN increases.

  • B

    (2) Before: NN0\frac{N}{N_0} rises exponentially from 11 as tt increases. After: rr rises from the origin along an upward-curving (parabolic) graph as NN increases.

  • C

    (3) Before: NN0\frac{N}{N_0} rises from 00 rather than from 11 at t=0t = 0. After: rr rises from the origin along an upward-curving graph as NN increases.

  • D

    (4) Before: NN0\frac{N}{N_0} rises exponentially from 11 as tt increases. After: rr increases linearly with NN.

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