NEET Chemical Kinetics PYQ practice sheet

16 previous-year NEET Chemistry questions from Chemical Kinetics, newest papers first. Chemical Kinetics carries 19 of the Chemistry questions in NEET 2020 to 2026, so this is a good place to test yourself after revising the chapter. Marking: +4 correct, −1 wrong.

1. 1.

   RE-NEET 2026

   $2\mathrm{A} \xrightarrow{k} \mathrm{B}$ is a zero-order reaction, where $k = 1.0\ \mathrm{mol\,L^{-1}\,min^{-1}}$. If the initial concentration of A is $2$ M, then the time taken to complete $75\%$ of the reaction will be

   • (A)
     $0.75$ min
   • (B)
     $1.0$ min
   • (C)
     $2.0$ min
   • (D)
     $1.5$ min
2. 2.

   RE-NEET 2026

   For an elementary chemical reaction, the Arrhenius plot is given below. Figure: a plot of $\ln k$ (vertical axis, marked $2, 4, 6, 8$) against $1/T$ (horizontal axis). It is a straight line with a negative slope that cuts the $\ln k$ axis at $\ln k = 6$. If the energy of activation is $6.64$ kJ $\mathrm{mol^{-1}}$ and $R = 8.3\ \mathrm{J\,K^{-1}\,mol^{-1}}$, the temperature at which the rate constant becomes $e^2\ \mathrm{min^{-1}}$, is

   • (A)
     $125$ K
   • (B)
     $200$ K
   • (C)
     $150$ K
   • (D)
     $250$ K
3. 3.

   NEET 2026

   Match List I with List II: List-I (Order of reaction): A. Zero order, B. First order, C. Second order, D. Third order List-II (Unit of rate constant): I. $\mathrm{mol^{-1}\,L\,s^{-1}}$, II. $\mathrm{mol^{-2}\,L^{2}\,s^{-1}}$, III. $\mathrm{s^{-1}}$, IV. $\mathrm{mol\,L^{-1}\,s^{-1}}$ Choose the correct answer from the options given below:

   • (A)
     A-IV, B-II, C-I, D-III
   • (B)
     A-IV, B-III, C-II, D-I
   • (C)
     A-IV, B-III, C-I, D-II
   • (D)
     A-I, B-II, C-III, D-IV
4. 4.

   NEET 2026

   For a certain reaction $\mathrm{R\to Product}$, the plot of concentration [R] vs time has a negative slope as shown. The order of reaction is: The graph is a straight line starting from $[R_0]$ on the concentration axis and falling uniformly with time. The rate constant is $k=-\text{slope}$.

   • (A)
     2.5
   • (B)
     2
   • (C)
     1
   • (D)
     0
5. 5.

   NEET 2026

   Given below is an expression for the rate constant of a first-order reaction occurring at a certain temperature, $T$ (K).

   $$\ln k=14.34-\frac{1.25\times10^{4}}{T}$$

   The energy of activation in kcal mol$^{-1}$ for the reaction is: (Given: $k$ in s$^{-1}$, $R=1.987\ \text{cal mol}^{-1}\text{K}^{-1}$)

   • (A)
     12.42
   • (B)
     24.84
   • (C)
     18.63
   • (D)
     14.34
6. 6.

   NEET 2024

   Activation energy of any chemical reaction can be calculated if one knows the value of

   • (A)
     rate constant at two different temperatures.
   • (B)
     orientation of reactant molecules during collision.
   • (C)
     rate constant at standard temperature.
   • (D)
     probability of collision.
7. 7.

   NEET 2024

   Which plot of $\ln k$ vs $\dfrac{1}{T}$ is consistent with Arrhenius equation?

   • (A)
     
   • (B)
     
   • (C)
     
   • (D)
     
8. 8.

   NEET 2024

   The rate of a reaction quadruples when temperature changes from $27^\circ$C to $57^\circ$C. Calculate the energy of activation. Given $R=8.314\ \mathrm{J\ K^{-1}mol^{-1}}$, $\log4=0.6021$

   • (A)
     3.80 kJ/mol
   • (B)
     38.04 kJ/mol
   • (C)
     3804 kJ/mol
   • (D)
     380.4 kJ/mol
9. 9.

   NEET 2023

   Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R : Assertion A : A reaction can have zero activation energy. Reasons R : The minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to threshold value, is called activation energy. In the light of the above statements, choose the correct answer from the options given below :

   • (A)
     A is false but R is true.
   • (B)
     Both A and R are true and R is the correct explanation of A.
   • (C)
     Both A and R are true but R is NOT the correct explanation of A.
   • (D)
     A is true but R is false.
10. 10.

    NEET 2023

    For a certain reaction, the rate $= k[\mathrm{A}]^2[\mathrm{B}]$, when the initial concentration of A is tripled keeping concentration of B constant, the initial rate would

    • (A)
      increase by a factor of three.
    • (B)
      decrease by a factor of nine.
    • (C)
      increase by a factor of six.
    • (D)
      increase by a factor of nine.
11. 11.

    NEET 2022

    The given graph is a representation of kinetics of a reaction (at constant temperature T, a horizontal straight line is obtained when $y$ is plotted against $x$). The $y$ and $x$ axes for zero and first order reactions, respectively, are:

    • (A)
      zero order (y = rate and x = concentration), first order (y = rate and x = $t_{1/2}$)
    • (B)
      zero order (y = concentration and x = time), first order (y = $t_{1/2}$ and x = concentration)
    • (C)
      zero order (y = concentration and x = time), first order (y = rate constant and x = concentration)
    • (D)
      zero order (y = rate and x = concentration), first order (y = $t_{1/2}$ and x = concentration)
12. 12.

    NEET 2022

    For a first order reaction $\mathrm{A\rightarrow Products}$, the initial concentration of A is 0.1 M, which becomes 0.001 M after 5 minutes. The rate constant for the reaction in $\text{min}^{-1}$ is:

    • (A)
      0.2303
    • (B)
      1.3818
    • (C)
      0.9212
    • (D)
      0.4606
13. 13.

    NEET 2021

    For a reaction $\mathrm{A \rightarrow B}$, enthalpy of reaction is $-4.2\ \mathrm{kJ\,mol^{-1}}$ and enthalpy of activation is $9.6\ \mathrm{kJ\,mol^{-1}}$. The correct potential energy profile for the reaction is shown in option.

    • (A)
      
    • (B)
      
    • (C)
      
    • (D)
      
14. 14.

    NEET 2021

    The slope of Arrhenius Plot $\left(\ln k\ \text{v/s}\ \dfrac{1}{T}\right)$ of first order reaction is $-5\times10^{3}\ \mathrm{K}$. The value of $E_a$ of the reaction is. Choose the correct option for your answer. [Given $R = 8.314\ \mathrm{J\,K^{-1}mol^{-1}}$]

    • (A)
      $166\ \mathrm{kJ\,mol^{-1}}$
    • (B)
      $-83\ \mathrm{kJ\,mol^{-1}}$
    • (C)
      $83.0\ \mathrm{kJ\,mol^{-1}}$
    • (D)
      $41.5\ \mathrm{kJ\,mol^{-1}}$
15. 15.

    NEET 2020

    The rate constant for a first order reaction is $4.606\times10^{-3}\ \mathrm{s^{-1}}$. The time required to reduce $2.0$ g of the reactant to $0.2$ g is :

    • (A)
      100 s
    • (B)
      200 s
    • (C)
      500 s
    • (D)
      1000 s
16. 16.

    NEET 2020

    An increase in the concentration of the reactants of a reaction leads to change in :

    • (A)
      activation energy
    • (B)
      heat of reaction
    • (C)
      threshold energy
    • (D)
      collision frequency