Chemical Kinetics — JEE Main PYQs

Pre-exponential factors of two different reactions of same order are identical. Let activation energy of first reaction exceeds the activation energy of second reaction by $20\mathrm{kJ}{\mathrm{mol}}^{-1}$. If ${\mathrm{k}}_1$ and ${\mathrm{k}}_2$ are the rate constants of fir …

A → products (First order reaction).

Three sets of experiment were performed for a reaction under similar experimental conditions.
Run $1\Rightarrow 100\mathrm{mL}$ of 10 M solution of reactant A
Run $2\Rightarrow 200\mathrm{mL}$ of 10 M solution of reactant A
Run …

The temperature at which the rate constants of the given below two gaseous reactions become equal is
____ K. (Nearest integer).
$\mathrm{X}⟶\mathrm{Y}{\mathrm{k}}_1=10^6{\mathrm{e}}^{\frac{-30000}{\mathrm{T}}}$ …

Decomposition of A is a first order reaction at $\mathrm{T}(\mathrm{K})$ and is given by $\mathrm{A}(\mathrm{g})\to \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$. In a closed 1 L vessel, 1 bar $\mathrm{A}(\mathrm{g})$ is allowed to decompose at $\mathrm{T}(\mathrm{K})$. …

Correct statements regarding Arrhenius equation among the following are :
(A) Factor $e^{-\mathrm{Ea}/\mathrm{RT}}$ corresponds to fraction of molecules having kinetic energy less than Ea.
(B) At a given temperature, lower the Ea, faster is the reaction.
(C) Increase in tempe …

Consider $\mathrm{A}\stackrel{k_1}{\to }\mathrm{B}$ and $\mathrm{C}\stackrel{k_2}{\to }\mathrm{D}$ are two reactions. If the rate constant $(k_1)$ of the $\mathrm{A}\to \mathrm{B}$ reaction can be expressed by the following equation …

For the thermal decomposition of reaction $\mathrm{AB}(\mathrm{g})$, the following is constructed.

The half life of the reaction is 'x' min.
$x=$ ____ min. (Nearest integer)

Observe the following reactions at T(K).
I. A → products.
II. 5Br⁻(aq) + BrO₃⁻(aq) + 6H⁺(aq) → 3Br₂(aq) + 3H₂O(l)
Both the reactions are started at 10:00 am. The rates of these reactions at 10:10 am are the same. The value of −Δ[Br⁻]/Δt at 10:10 am is 2 × 10⁻⁴ mol L⁻¹ min⁻¹. The …

$\mathrm{A}\to \mathrm{D}$ is an endothermic reaction occurring in three steps (elementary).
(i) $\mathrm{A}\to \mathrm{B}\Delta {\mathrm{H}}_{\mathrm{i}}=+\mathrm{ve}$
(ii) $\mathrm{B}\to \mathrm{C}\Delta {\mathrm{H}}_{\mathrm{ii}}=-\mathrm{ve}$
(i …

At $27^{\circ }\mathrm{C}$ in presence of a catalyst, activation energy of a reaction is lowered by $10\mathrm{kJ}{\mathrm{mol}}^{-1}$. The logarithm ratio of $\frac{\mathrm{k}\text{ (catalysed) }}{\mathrm{k}\text{ (uncatalysed) }}$ is ....
(Consider that the frequency factor …

The half-life of ${}^{65}\mathrm{Zn}$ is 245 days. After x days, $75\%$ of original activity remained. The value of x in days is ____. (Nearest integer)
(Given: $\log 3=0.4771$ and $\log 2=0.3010$)

An organic compound undergoes first order decomposition. The time taken for decomposition to ${\left(\frac{1}{8}\right)}^{\text{th }}$ and ${\left(\frac{1}{10}\right)}^{\text{th }}$ of its initial concentration are $t_{1/8}$ and $t_{1/10}$ respectively.

What is the val …

$\mathrm{A}\to \mathrm{B}$ (first reaction)
$\mathrm{C}\to \mathrm{D}$ (second reaction)
Consider the above two first-order reactions. The rate constant for first reaction at 500 K is double of the same at 300 K. At 500 K, 50% of the reaction becomes complete in 2 h …

$t_{100\%}$ is the time required for the $100\%$ completion of the reaction while $t_{1/2}$ is the time required for $50\%$ of the reaction to be completed. Which of the following option correctly represents the relation between $t_{100\%}$ and $t_{1/2}$ for zero and first order …

For reaction $\mathrm{A}\to \mathrm{P}$, rate constant $\mathrm{k}=1.5\times 10^3{\mathrm{s}}^{-1}$ at $27^{\circ }\mathrm{C}$. If activation energy for the above reaction is $60\mathrm{kJ}{\mathrm{mol}}^{-1}$, then the temperature (in ${}^{\circ }\mathrm{C}$) at w …

Consider the first order reaction $\mathrm{R}\to \mathrm{P}$.

The fraction of molecules decomposed in the given first order reaction can be expressed as

Consider the reaction $\mathrm{aX}\to \mathrm{bY}$, for which the rate constant at $30^{\circ }\mathrm{C}$ is $1\times 10^{-3}{\mathrm{mol}}^{-1}{\mathrm{L}\mathrm{s}}^{-1}$. Which of the following statements are true?
A. When concentration of 'X' is increased to four times, the rat …

Consider the following gas phase reaction being carried out in a closed vessel at $25^{\circ }\mathrm{C}$.
$2\mathrm{A}(\mathrm{g})\to 4\mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$
| time (min) | total pressure of the system (mm Hg) ||------------|-------- …

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?

For a first order reaction $\mathrm{A}\to \mathrm{B}$

$\mathrm{x}=$ _____ min. (Nearest integer)

First order gas phase reaction
$\mathrm{A}\to \mathrm{B}+\mathrm{C}$
$p_i=$ initial pressure of gas $A,p_t=$ total pressure of the reaction mixture at time t
Expression of rate constant ( k ) is

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 : $\log 2=0.3010$ )

For a reaction $\mathrm{A}\to \mathrm{P}$ at TK, the half life $({\mathrm{t}}_{1/2})$ is plotted as a function of initial concentration $[\mathrm{A}{]}_0$ of A as given below:

The value of x in the given figure is _____ s
(Nearest integer)

Sucrose hydrolyses in acidic medium into glucose and fructose by first order rate law with ${\mathrm{t}}_{1/2}=3$ hour. The percentage of sucrose remaining after 6 hours is _____. (Nearest integer)
(Given : $\log 2=0.3010$ and $\log 3=0.4771$)

Decomposition of a hydrocarbon follows the equation $k=(5.5\times 10^{11}{\mathrm{s}}^{-1})e^{\frac{-28000\mathrm{K}}{T}}$. The activation energy of reaction is $\_\_\_\_$ ${\mathrm{kJ}\mathrm{mol}}^{-1}$. (Nearest Integer)
Given : $R=8.3{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$

Given below are two statements :
$\mathrm{R}=8.314\mathrm{J}{\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}$ and $1\mathrm{cal}=4.2\mathrm{J}$

Statement I : When $\mathrm{Ea}=12.6\mathrm{kcal}/\mathrm{mol}$, the room temperature rate constant is doubled by a $10^{\circ }\mathrm{C}$ increase …

Which of the following statement is not true for radioactive decay?

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

The molecule A changes into its isomeric form B by following a first order kinetics at a temperature of 1000 K . If the energy barrier with respect to reactant energy for such isomeric transformation is …

Consider the given figure and choose the correct option :

For a reaction, ${\mathrm{N}}_2{\mathrm{O}}_{5(\mathrm{g})}\to 2{\mathrm{NO}}_{2(\mathrm{g})}+\frac{1}{2}{\mathrm{O}}_{2(\mathrm{g})}$ in a constant volume container, no products were present initially. The final pressure of the system when $50\%$ of reaction gets c …

Given below are two statements :

Statement(I) :

Statement(II) :

In the light of the above statements, choose the correct answer from the options given below :

Consider a complex reaction taking place in three steps with rate constants ${\mathrm{k}}_1,{\mathrm{k}}_2$ and ${\mathrm{k}}_3$ respectively. The overall rate constant k is given by the expression $\mathrm{k}=\sqrt{\frac{{\mathrm{k}}_1{\mathrm{k}}_3}{{\mathrm{k}}_2}}$. I …

For the thermal decomposition of ${\mathrm{N}}_2{\mathrm{O}}_5(\mathrm{g})$ at constant volume, the following table can be formed, for the reaction mentioned below : …

For a given reaction $\mathrm{R}\to \mathrm{P}$, ${\mathrm{t}}_{1/2}$ is related to $[\mathrm{A}{]}_0$ as given in table :

Given : $\log 2$ = 0.3 …

Which of the following graphs most appropriately represents a zero order reaction?

consider the elementary reaction
$\mathrm{A}(\mathrm{g})+\mathrm{B}(\mathrm{g})\to \mathrm{C}(\mathrm{g})+\mathrm{D}(\mathrm{g})$
If the volume of reaction mixture is suddenly reduced to $\frac{1}{3}$ of its initial volume, the reaction rate will become ' $x$ ' tim …

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?

The reaction ${\mathrm{A}}_2+{\mathrm{B}}_2\to 2\mathrm{AB}$ follows the mechanism
${\mathrm{A}}_2\underset{{\mathrm{k}}_{-1}}{\stackrel{{\mathrm{k}}_1}{\rightleftharpoons }}\mathrm{A}+\mathrm{A}$ (fast) …

Drug X becomes ineffective after $50\%$ decomposition. The original concentration of drug in a bottle was $16\mathrm{mg}/\mathrm{mL}$ which becomes 4 $\mathrm{mg}/\mathrm{mL}$ in 12 months. The expiry time of the drug in months is ______ .
Assume that the decompositio …

For the reaction $\mathrm{A}\to$ products.

The concentration of A at 10 minutes is $\_\_\_\_$ $\times 10^{-3}\mathrm{mol}{\mathrm{L}}^{-1}$ (nearest integer).
The reaction was started with $2.5\mathrm{mol}{\mathrm{L}}^{-1}$ of A.

Reactant A converts to product D through the given mechanism (with the net evolution of heat) :
$\mathrm{A}\to \mathrm{B}$ slow; $\Delta \mathrm{H}=+\mathrm{ve}$
$\mathrm{B}\to \mathrm{C}$ fast; $\Delta \mathrm{H}=-\mathrm{ve}$ …

For the reaction $\mathrm{A}\to \mathrm{B}$ the following graph was obtained. The time required (in seconds) for the concentration of A to reduce to $2.5\mathrm{g}{\mathrm{L}}^{-1}$ (if the initial concentration of A was $50\mathrm{g}{\mathrm{L}}^{-1}$ ) is _\ …

In a reaction $\mathrm{A}+\mathrm{B}\to \mathrm{C}$, initial concentrations of $A$ and $B$ are related as $[A{]}_0=8[B{]}_0$. The half lives of $A$ and $B$ are 10 min and 40 min . respectively. If they start to disappear at the same time, both following first order kinet …

Consider the following plots of log of rate constant k ($\log k$) vs $\frac{1}{T}$ for three different reactions. The correct order of activation energies of these reactions is

Half life of zero order reaction $\mathrm{A}\to$ product is 1 hour, when initial concentration of reaction is $2.0{\mathrm{mol}\mathrm{L}}^{-1}$. The time required to decrease concentration of A from 0.50 to $0.25{\mathrm{mol}\mathrm{L}}^{-1}$ is:

For $\overline{{\mathrm{A}}_2+{\mathrm{B}}_2\rightleftharpoons 2\mathrm{AB}}$
${\mathrm{E}}_{\mathrm{a}}$ for forward and backward reaction are 180 and $200\mathrm{kJ}{\mathrm{mol}}^{-1}$ respectively
If catalyst lowers ${\mathrm{E}}_{\mathrm{a}}$ for both reaction by …

Rate law for a reaction between A and B is given by
$\mathrm{R}=\mathrm{k}[\mathrm{A}{]}^{\mathrm{n}}[\mathrm{B}{]}^{\mathrm{m}}$
If concentration of A is doubled and concentration of B is halved from their initial value, the ratio of new rate of reaction to the initial rate of rea …

$\mathrm{A}(\mathrm{g})\to \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$ is a first order reaction.

The reaction was started with react …

Reaction $\mathrm{A}(\mathrm{g})\to 2\mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$ is a first order reaction. It was started with pure A
| 10 | 160 …

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 (r) was found to be proportional with the square of the existing number of bact …