Chemical Kinetics — JEE Main PYQs

In a first order decomposition reaction, the time taken for the decomposition of reactant to one fourth and one eighth of its initial concentration are $t_1$ and $t_2(s)$, respectively. The ratio $t_1/t_2$ will :

Consider the following transformation involving first order elementary reaction in each step at constant temperature as shown below. …

Consider the following reaction, the rate expression of which is given below
$\mathrm{A}+\mathrm{B}\to \mathrm{C}$
rate $=k[\mathrm{A}{]}^{1/2}[\mathrm{B}{]}^{1/2}$
The reaction is initiated by taking 1 M concentration A and B each. If the rate constant (k) is …

During Kinetic study of reaction $2\mathrm{A}+\mathrm{B}\to \mathrm{C}+\mathrm{D}$, the following results were obtained :
| I | 0.1 | 0.1 | …

Consider the following single step reaction in gas phase at constant temperature.
$2{\mathrm{A}}_{(\mathrm{g})}+{\mathrm{B}}_{(\mathrm{g})}\to {\mathrm{C}}_{(\mathrm{g})}$
The initial rate of the reaction is recorded as $r_1$ when the reaction starts with 1.5 atm press …

Time required for $99.9\%$ completion of a first order reaction is ____ time the time required for completion of $90\%$ reaction.(nearest integer).

Consider the two different first order reactions given below
$\mathrm{A}+\mathrm{B}\to \mathrm{C}$ (Reaction 1)
$\mathrm{P}\to \mathrm{Q}$ (Reaction 2)
The ratio of the half life of Reaction 1 : Reaction 2 is $5:2$. If ${\mathrm{t}}_1$ and …

For a reaction $\mathrm{A}\stackrel{{\mathrm{K}}_1}{\to }\mathrm{B}\stackrel{{\mathrm{K}}_2}{\to }\mathrm{C}$

If the rate of formation of B is set to be zero then the concentration of B is given by :

Consider the following reaction
$\mathrm{A}+\mathrm{B}\to \mathrm{C}$
The time taken for A to become $1/4^{\text{th}}$ of its initial concentration is twice the time taken to become 1/2 of the same. Also, when the change of concentration of B is plotted against time, the …

Given below are two statements :

Statement I : The rate law for the reaction $\mathrm{A}+\mathrm{B}\to \mathrm{C}$ is rate $(\mathrm{r})=\mathrm{k}[\mathrm{A}{]}^2[\mathrm{B}]$. When the concentration of both A and B is doubled, the reaction rate is increased "x" t …

Consider the following first order gas phase reaction at constant temperature
$\mathrm{A}(\mathrm{g})\to 2\mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$
If the total pressure of the gases is found to be 200 torr after 23 sec . and 300 torr upon the complete decompos …

Consider the following data for the given reaction
$2{\mathrm{HI}}_{(\mathrm{g})}\to {\mathrm{H}}_{2(\mathrm{g})}+{\mathrm{I}}_{2(\mathrm{g})}$
| Rate …

The following data were obtained during the first order thermal decomposition of a gas A at constant volume:
A(g) → 2B(g) + C(g)

The rate …

The ratio of $\frac{{}^{14}\mathrm{C}}{{}^{12}\mathrm{C}}$ in a piece of wood is $\frac{1}{8}$ part that of atmosphere. If half life of ${}^{14}\mathrm{C}$ is 5730 years, the age of wood sample is ____ years.

Time required for completion of $99.9\%$ of a First order reaction is ____ times of half life $\left({\mathrm{t}}_{1/2}\right)$ of the reaction.

For a reaction taking place in three steps at same temperature, overall rate constant $\mathrm{K}=\frac{{\mathrm{K}}_1{\mathrm{K}}_2}{{\mathrm{K}}_3}$. If ${\mathrm{Ea}}_1,{\mathrm{Ea}}_2$ and ${\mathrm{Ea}}_3$ are 40,50 and $60\mathrm{kJ}/\mathrm{mol}$ respective …

The half-life of radioisotopic bromine - 82 is 36 hours. The fraction which remains after one day is _____ $\times 10^{-2}$.
(Given antilog $0.2006=1.587$)

Integrated rate law equation for a first order gas phase reaction is given by (where ${\mathrm{P}}_{\mathrm{i}}$ is initial pressure and ${\mathrm{P}}_{\mathrm{t}}$ is total pressure at time t )

The rate of first order reaction is $0.04\mathrm{mol}{\mathrm{L}}^{-1}{\mathrm{s}}^{-1}$ at 10 minutes and $0.03\mathrm{mol}{\mathrm{L}}^{-1}{\mathrm{s}}^{-1}$ at 20 minutes after initiation. Half life of the reaction is ____ minutes. (Given …

r = k[A] for a reaction, 50% of A is decomposed in 120 minutes. The time taken for 90% decomposition of A is _____ minutes.

${\mathrm{NO}}_2$ required for a reaction is produced by decomposition of ${\mathrm{N}}_2{\mathrm{O}}_5$ in ${\mathrm{CCl}}_4$ as by equation $2{\mathrm{N}}_2{\mathrm{O}}_{5(\mathrm{g})}\to 4{\mathrm{NO}}_{2(\mathrm{g})}+{\mathrm{O}}_{2(\mathrm{g})}$
The initia …

Consider the following reaction that goes from A to B in three steps as shown below:-

Choose the correct

The correct reaction profile diagram for a positive catalyst reaction.

The number of incorrect statement/s from the following is ______

A. The successive half lives of zero order reactions decreases with time.

B. A substance appearing as reactant in the chemical equation may not affect the rate of reaction

C. Order and molecularity of a chemical …

The number of given statement/s which is/are correct is ______
(A) The stronger the temperature dependence of the rate constant, the higher is the activation energy.
(B) If a reaction has zero activation energy, its rate is independent of temperature.
(C) The stronger the tempera …

A molecule undergoes two independent first order reactions whose respective half lives are 12 min and 3 min . If both the reactions are occurring then the time taken for the $50\%$ consumption of the reactant is ____ min. (Nearest integer)

$\mathrm{KClO}{}_3+6\mathrm{FeSO}{}_4+3\mathrm{H}{}_2\mathrm{SO}{}_4\to \mathrm{KCl}+3\mathrm{Fe}{}_2(\mathrm{SO}{}_4){}_3+3\mathrm{H}{}_2\mathrm{O}$

The above reaction was studied at 300 K by monitoring the concentration of $\mathrm{FeSO}{}_4$ in which initial concentration was 10 M and after half an hour became 8.8 M. The rate of production of $\mathrm{Fe}{}_2(\mathrm{SO}{}_4){}_3$ is …

For a chemical reaction $\mathrm{A}+\mathrm{B}\to$ Product, the order is 1 with respect to A and B .
| 0.4 …

The reaction $2\mathrm{NO}+{\mathrm{Br}}_2\to 2\mathrm{NOBr}$
takes places through the mechanism given below:
$\mathrm{NO}+{\mathrm{Br}}_2\iff {\mathrm{NOBr}}_2$ (fast)
${\mathrm{NOBr}}_2+\mathrm{NO}\to 2\mathrm{NOBr}$ (slow)

The overall order of th …

$t_{87.5}$ is the time required for the reaction to undergo $87.5\%$ completion and $t_{50}$ is the time required for the reaction to undergo 50% completion. The relation between $t_{87.5}$ and $t_{50}$ for a first order reaction is …

$\mathrm{A}(\mathrm{g})\to 2\mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$ is a first order reaction. The initial pressure of the system was found to be 800 mm Hg which increased to 1600 mm Hg after 10 min. The total pressure of the system after 30 min will be ____ m …

For a reversible reaction $\mathrm{A}\rightleftharpoons \mathrm{B}$, the $\Delta {\mathrm{H}}_{\text{forward}}$ reaction $=20\mathrm{kJ}{\mathrm{mol}}^{-1}$. The activation energy of the uncatalysed forward reaction is $300\mathrm{kJ}{\mathrm{mol}}^{-1}$. When the reac …

A and B are two substances undergoing radioactive decay in a container. The half life of A is 15 min and that of B is 5 min. If the initial concentration of B is 4 times that of A and they both start decaying at the same time, how much time will it take for the concentration of b …

The number of correct statement/s from the following is ______.
A. Larger the activation energy, smaller is the value of the rate constant.
B. The higher is the activation energy, higher is the value of the temperature coefficient.
C. At lower temperatures, increase in temperatur …

A student has studied the decomposition of a gas ${\mathrm{AB}}_3$ at $25^{\circ }\mathrm{C}$. He obtained the following data.

The order of the reaction is

For the first order reaction $\mathrm{A}\to \mathrm{B}$ the half life is 30 min. The time taken for $75\%$ completion of the reaction is ______ min. (Nearest integer)

Given: $\log 2=0.3010$
$\log 3=0.4771$
$\log 5=0.6989$

A first order reaction has the rate constant, $\mathrm{k}=4.6$
$\times 10^{-3}{\mathrm{s}}^{-1}$. The number of correct statement/s from the following is/are ____.

Given : $\log 3=0.48$
A. Reaction completes in 1000 s.
B. The reaction has a half-life of 500 s.
C. The t …

An indicator 'X' is used for studying the effect of variation in concentration of iodide on the rate of reaction of iodide ion with ${\mathrm{H}}_2{\mathrm{O}}_2$ at room temp. The indicator 'X' forms blue colored complex with compound 'A' present in the solution. The indicator …

For conversion of compound $\mathrm{A}\to \mathrm{B}$, the rate constant of the reaction was found to be $4.6\times 10^{-5}\mathrm{L}{\mathrm{mol}}^{-1}{\mathrm{s}}^{-1}$. The order of the reaction is ____。

If compound A reacts with B following first order kinetics with rate constant $2.011\times 10^{-3}{\mathrm{s}}^{-1}$. The time taken by A (in seconds) to reduce from 7 g to 2 g will be ______. (Nearest Integer)
$[\log 5=0.698,\log 7=0.845,\log 2=0.301]$

$\mathrm{A}\to \mathrm{B}$

The above reaction is of zero order. Half life of this reaction is 50 min . The time taken for the concentration of A to reduce to one-fourth of its initial value is $\_\_\_\_$ min.
(Nearest integer)

The rate constant for a first order reaction is $20{\min }^{-1}$. The time required for the initial concentration of the reactant to reduce to its $\frac{1}{32}$ level is ____ $\times 10^{-2}\min$. (Nearest integer)
(Given : $\ln 10=2.303$
$\log 2=0.3010$)

An organic compound undergoes first order decomposition. If the time taken for the 60% decomposition is 540 s, then the time required for $90\%$ decomposition will be is ____ s. (Nearest integer).

Given : $\ln 10=2.3;\log 2=0.3$

$\mathrm{A}\to \mathrm{B}$

The rate constants of the above reaction at 200 K and 300 K are $0.03{\min }^{-1}$ and $0.05{\min }^{-1}$ respectively. The activation energy for the reaction is ______ J (Nearest integer)

(Given: $\ln 10=2.3$ …

Assuming $1\mu \mathrm{g}$ of trace radioactive element X with a half life of 30 years is absorbed by a growing tree. The amount of X remaining in the tree after 100 years is ____ $\times 10^{-1}\mu \mathrm{g}$.
[Given : $\ln 10=2.303;\log 2=0.30$ ]

For kinetic study of the reaction of iodide ion with ${\mathrm{H}}_2{\mathrm{O}}_2$ at room temperature:
(A) Always use freshly prepared starch solution.
(B) Always keep the concentration of sodium thiosulphate solution less than that of KI solution.
(C) Record the time immediat …

For the given first order reaction
$A\to B$
the half life of the reaction is 0.3010 min. The ratio of the initial concentration of reactant to the concentration of reactant at time 2.0 min will be equal to $\_\_\_\_$. (Nearest integer)

For a reaction, given below is the graph of $\ln \mathrm{k}$ vs $\frac{1}{\mathrm{T}}$. The activation energy for the reaction is equal to ____ cal mol${}^{-1}$. (Nearest integer).
(Given : $\mathrm{R}=2\mathrm{cal}{\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}$)

$2\mathrm{NO}+2{\mathrm{H}}_2\to {\mathrm{N}}_2+2{\mathrm{H}}_2\mathrm{O}$

The above reaction has been studied at $800^{\circ }\mathrm{C}$. The related data are given in the table below

| Reaction serial number | Initial pressure of ${\mathrm{H}}_2$ / kPa | Initia …

The half life for the decomposition of gaseous compound A is 240 s when the gaseous pressure was 500 Torr initially. When the pressure was 250 Torr, the half life was found to be 4.0 min. The order of the reaction is...... (Nearest integer)