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Chemical Kinetics · Question 44

JEE Main 2025 (Online) 28th January Evening ShiftMCQEasy📈 Topic in 29% papers+4−1
1

For bacterial growth in a cell culture, growth law is very similar to the law of radioactive decay. Which of the following graphs is most suitable to represent bacterial colony growth? Where N - Number of bacteria at any time, N0 - Initial number of bacteria.

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(3) [figure]

Solution

Radioactive decay: dNdt = -kN. Bacterial growth follows the same first-order law, but the number increases:

dNdt = +kN

N0N dNN = k 0t dt

NN0 = kt

NN0 = ekt

At t = 0, NN0 = 1 (a non-zero intercept on the y-axis), and NN0 then rises exponentially (ever more steeply) with time.

Graph (1) is exponential decay, graph (2) is a linear fall and graph (4) rises from zero and levels off; only graph (3) starts above zero and increases exponentially.

Answer: (3)

JEE Main 2025 (Online) 28th January Evening Shift

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2

Given below are two statements : R = 8.314 J K-1 mol-1 and 1 cal = 4.2 J In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
JEE Main 2026 (Online) 8th April Evening Shift
3

Sucrose hydrolyses in acidic medium into glucose and fructose by first order rate law with t1/2 = 3 hour. The percentage of sucrose remaining after 6 hours is . (Nearest integer) (Given : log 2 = 0.3010 and log 3 = 0.4771)

JEE Main 2026 (Online) 6th April Morning Shift
4

Decomposition of a hydrocarbon follows the equation k = (5.5 1011 s-1) e-28000 K/T. The activation energy of reaction is kJ mol-1. (Nearest Integer) Given : R = 8.3 J K-1 mol-1

JEE Main 2026 (Online) 6th April Evening Shift
5

First order gas phase reaction A B + C pi = initial pressure of gas A, pt = total pressure of the reaction mixture at time t Expression of rate constant (k) is

  1. 1t pi2pi - pt
  2. 1t 2pipi - pt
  3. 1t pi3pi - 2pt
  4. 1t 3pi4pi - pt
JEE Main 2026 (Online) 5th April Morning Shift
6

If the half life of a first order reaction is 6.93 minutes then the time required for completion of 99% of the reaction will be minutes. (Given : log 2 = 0.3010)

JEE Main 2026 (Online) 5th April Morning Shift
7

For a reaction A → P at T K, the half life (t1/2) is plotted as a function of initial concentration [A]0 of A as given below. [figure] The value of x in the given figure is s (Nearest integer)

JEE Main 2026 (Online) 5th April Evening Shift
8

Consider the first order reaction R P. The fraction of molecules decomposed in the given first order reaction can be expressed as

  1. 1 - ek1t
  2. 1 + ek1t
  3. 1 + e-k1t
  4. 1 - e-k1t
JEE Main 2026 (Online) 4th April Morning Shift
9

Consider the given graph showing variation of reactant concentration with time. Three different reactions were started with identical initial concentration of reactants. Which of the following statement is correct? [figure]

  1. The order of all the three reactions is same.
  2. The rate constant of reaction 3 is larger than the rate constant of reaction 2 if the order of reaction is same for both.
  3. The SI unit of rate constant of reaction 1 is s-1.
  4. Thermal decomposition of HI on gold surface is an example of reaction 2.
JEE Main 2026 (Online) 4th April Evening Shift
10

For a first order reaction A B arrayll t/min & [A]/M \ 0 & 0.6500 \ x & 0.0650 \ 20 & 0.00065 array x = min. (Nearest integer)

JEE Main 2026 (Online) 4th April Evening Shift
11

t100\% is the time required for the 100% completion of the reaction while t1/2 is the time required for 50% of the reaction to be completed. Which of the following option correctly represents the relation between t100\% and t1/2 for zero and first order reactions respectively ?

  1. t100\% = (t1/2)2 and t100\% = (t1/2)-
  2. t100\% = 2t1/2 and t100\% = (t1/2)
  3. t100\% = 2t1/2 and t100\% = (2t1/2)2
  4. t100\% = (t1/2) and t100\% = 2t1/2
JEE Main 2026 (Online) 2nd April Morning Shift

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