Chemical Kinetics · Chemistry · COMEDK

Start Practice

MCQ (Single Correct Answer)

1
The hydrogenation of Ethyne is carried out at 600 K . The same reaction when carried out in presence of a catalyst maintaining the same rate constant, the temperature required is only 400 K . If the catalyst lowers the Activation energy of the reaction by $20 \mathrm{~kJ} / \mathrm{mol}$, what is the value of $\mathrm{E}_{\mathrm{a}}$ ?
COMEDK 2025 Afternoon Shift
2
The time needed for completion of $80 \%$ is $y$ times the half-life period of a first order reaction. What is the value of $y$ ?
COMEDK 2025 Afternoon Shift
3
Which one of the following is incorrect?
COMEDK 2025 Afternoon Shift
4

(i) and (ii) are 2 chemical reactions carried out at TK.

(i). $\mathrm{X} \rightarrow \mathrm{Y}+\mathrm{W}$ with $\mathrm{k}_1$ as rate constant.

(ii). $\mathrm{X} \rightarrow \mathrm{Z}+\mathrm{W}$ with $k_2$ as rate constant.

The Activation energy for reaction (ii) is 3 times that of reaction (i). What is the expression for $k_1$ ?

COMEDK 2025 Afternoon Shift
5
The rate constant for a zero order reaction $\mathrm{A} \rightarrow \mathrm{B}+\mathrm{C}$ is $6.0 \times 10^{-3} \mathrm{molL}^{-1} \mathrm{~s}^{-1}$. What would be the time taken for the initial concentration of A to decrease from 0.2 M to 0.024 M ?
COMEDK 2025 Afternoon Shift
6

Two statements, One Assertion (A) and the other Reason (R) are given. Choose the right option.

Assertion: The rate constant $(\mathrm{k})$ for a chemical reaction gets nearly doubled for a $10^0$ rise in temperature.

Reason: The number of bimolecular collisions between reactant molecules increase with increase in temperature

COMEDK 2025 Morning Shift
7
Two chemical reactions of the same order have equal Frequency factor value. Their Activation energies differ by $26.8 \mathrm{~kJ} / \mathrm{mol}$. At 300 K if $k_2=x k_1$ find the value of $x$.
COMEDK 2025 Morning Shift
8
For a given reaction of the type $\frac{3}{5} X(a q) \rightarrow \frac{1}{2} Y(a q)+Z(g)$, the correct expression for the rate of disappearance of $X$ with reference to $Y$ is ___________
COMEDK 2025 Morning Shift
9
$\mathrm{X} \rightarrow 2 \mathrm{Y}$ is a first order reaction where $1.0 \mathrm{~mol} / \mathrm{L}$ of the reactant yields $0.4 \mathrm{~mol} / \mathrm{L}$ of Y in 200 minutes. Calculate the half-life period of the reaction in minutes.
COMEDK 2025 Morning Shift
10

The following results were obtained during study of the reaction $2 \mathrm{NO}(\mathrm{g})+\mathrm{Cl}_2(\mathrm{~g}) \rightarrow 2 \mathrm{NOCl}(\mathrm{g})$. Determine the value of $[\mathrm{X}]$ in $\mathrm{mol} / \mathrm{L}$

Experiment [NO]
mol / L
[Cl$_2$]
mol / L
Initial rate of formation. [NOCl]
mol / L / min
I 0.2 0.2 $6.0 \times 10^{-3}$
II 0.2 0.4 $2.4 \times 10^{-2}$
III 0.4 0.2 $1.2 \times 10^{-2}$
IV X 0.6 $1.35 \times 10^{-1}$

COMEDK 2025 Morning Shift
11

For a given reaction, ,$$\mathrm{X}(\mathrm{g})+\mathrm{Y}(\mathrm{g} \rightarrow \mathrm{Z}(\mathrm{g})$$, the order of reaction with respect to $$\mathrm{X}$$ and $$\mathrm{Y}$$ are $$\mathrm{m}$$ and $$\mathrm{n}$$ respectively. If the concentration of $$\mathrm{X}$$ is tripled and that of $$\mathrm{Y}$$ is decreased to one third, what is the ratio between the new rate to the original rate of the reaction?

COMEDK 2024 Evening Shift
12

For a reaction $$5 X+Y \rightarrow 3 Z$$, the rate of formation of $$Z$$ is $$2.4 \times 10^{-5} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$$ Calculate the average rate of disappearance of $$\mathrm{X}$$.

COMEDK 2024 Evening Shift
13

In the presence of a catalyst at a given temperature of $$27^{\circ} \mathrm{C}$$, the Activation energy of a specific reaction is reduced by $$100 \mathrm{~J} / \mathrm{mol}$$. What is the ratio between the rate constants for the catalysed $$(\mathrm{k}_2)$$ and uncatalysed $$(\mathrm{k}_1)$$ reactions?

COMEDK 2024 Evening Shift
14

The following data was recorded for the decomposition of XY compound at 750K

[XY] mol / L Rate of decomposition of XY mol / L s
0.4 $$5.5\times10^{-7}$$
0.8 $$22.0\times10^{-7}$$
1.2 $$49.5\times10^{-7}$$

What is the order of reaction with respect to decomposition of XY?

COMEDK 2024 Evening Shift
15

The Activation energy for the reaction $$A \rightarrow B+C$$, at a temperature $$\mathrm{TK}$$ was $$0.04606 \mathrm{~RT} \mathrm{~J} / \mathrm{mol}$$. What is the ratio of Arrhenius factor to the Rate constant for this reaction?

COMEDK 2024 Evening Shift
16

The temperature $$(\mathrm{T})$$ and rate constant $$(\mathrm{k})$$ for a first order reaction $$\mathrm{R} \rightarrow \mathrm{P}$$, was found to follow the equation $$\log \mathrm{k}=-(2000) \frac{1}{\mathrm{~T}}+8.0$$. The pre-exponential factor '$$\mathrm{A}$$' and activation energy $$\mathrm{E}_{\mathrm{a}}$$, respectively are: [Given: $$\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$$]

COMEDK 2024 Afternoon Shift
17

Given below a first order reaction in the gas phase

$$\mathrm{A}(\mathrm{g}) \rightarrow \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$$

If the initial pressure of the system is $$\mathrm{P}_{\mathrm{i}}$$ and the total pressure at $$\mathrm{t}$$ seconds is $$\mathrm{P}_{\mathrm{t}}$$, the rate constant $$\mathrm{k}$$ for the reaction is:

COMEDK 2024 Afternoon Shift
18

For the reaction, $$\mathrm{A}+3 \mathrm{~B} \rightarrow 2 \mathrm{C}+\mathrm{D}$$, the concentration of $$\mathrm{A}$$ changes from 0.0150 to 0.0125 in 1 minute. The rate of formation of $$\mathrm{C}$$ in $$\mathrm{mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$$ is:

COMEDK 2024 Afternoon Shift
19

The rate of appearance of bromine is related to the disappearance of bromide ion in the equation given below is:

$$\mathrm{BrO}_3^{-} \text {(aq) }+5 \mathrm{Br}^{-} \text {(aq) }+6 \mathrm{H}^{+} \rightarrow 3 \mathrm{Br}_2(\mathrm{l})+3 \mathrm{H}_2 \mathrm{O}(\mathrm{l})$$

COMEDK 2024 Afternoon Shift
20

The half-life for a zero order reaction is

COMEDK 2024 Afternoon Shift
21

The time required for $$80 \%$$ of a first order reaction is "$$y$$" times the half-life period of the same reaction. What is the value of "$$y$$"?

COMEDK 2024 Morning Shift
22

The rate constant for the reaction $$\mathrm{A} \rightarrow \mathrm{B}+\mathrm{C}$$ at $$500 \mathrm{~K}$$ is given as $$0.004 \mathrm{~s}^{-1}$$. At what temperature will the rate constant become $$0.014 \mathrm{~s}^{-1}$$ ? $$\mathrm{E}_{\mathrm{a}}$$ for the reaction is $$18.231 \mathrm{~kJ}$$.

COMEDK 2024 Morning Shift
23

For the reaction $$\mathrm{Cl}_{2(\mathrm{~g})}+2 \mathrm{NO}_{(\mathrm{g})} \rightarrow 2 \mathrm{NOCl}_{(\mathrm{g})}$$, the following data was obtained:

Experiment No. Initial concentration of $$\mathrm{Cl_2}$$ ($$\mathrm{M}$$) Initial concentration of $$\mathrm{NO}$$ ($$\mathrm{M}$$) Initial reaction rate ($$\mathrm{M}$$/min)
I 0.15 0.15 0.60
II 0.30 0.15 1.20
III 0.15 0.3 2.40
IV 0.25 0.25 2.78

Identify the order of the reaction with respect to $$\mathrm{Cl}_2, \mathrm{NO}$$ and the value of Rate constant.

COMEDK 2024 Morning Shift
24

Given below are 4 graphs [A], [B], [C] and [D]

COMEDK 2024 Morning Shift Chemistry - Chemical Kinetics Question 21 English

Identify the 2 graphs that represent a Zero order reaction?

COMEDK 2024 Morning Shift
25

A given chemical reaction is represented by the following stoichiometric equation.

$$3 X+2 Y+\frac{5}{2} Z \rightarrow P_1+P_2+P_3$$

The rate of reaction can be expressed as _________.

COMEDK 2024 Morning Shift
26

How much faster would a reaction proceed at $$25^{\circ} \mathrm{C}$$ than at $$0^{\circ} \mathrm{C}$$ if the activation energy is $$65 \mathrm{~kJ}$$?

COMEDK 2023 Morning Shift
27

At $$300 \mathrm{~K}$$, the half-life period of a gaseous reaction at an initial pressure of $$40 \mathrm{~kPa}$$ is 350 s. When pressure is $$20 \mathrm{~kPa}$$, the half-life period is 175 s. What is the order of the reaction?

COMEDK 2023 Morning Shift
28

For a reaction, $$2 A+B \longrightarrow$$ products, If concentration of $$B$$ is kept constant and concentration of $$A$$ is doubled then rate of reaction is

COMEDK 2023 Morning Shift
29

A first order reaction proceeds to $$90 \%$$ completion. What will be the approximate time taken for $$90 \%$$ completion in relation to $$t_{1 / 2}$$ of the reaction?

COMEDK 2023 Evening Shift
30

For a reaction of the type, $$2 \mathrm{X}+\mathrm{Y} \rightarrow \mathrm{A}+\mathrm{B}$$, the following is the data collected:

Experiment $$\mathrm{[X]}$$ $$\mathrm{[Y]}$$ Initial rate of formation of A
1 0.2 0.2 $$12.0\times10^{-3}$$
2 0.6 0.4 $$\mathrm{14.4\times10^{-2}}$$
3 0.6 0.8 $$5.76\times10^{-1}$$
4. 0.8 0.2 $$\mathrm{4.8\times10^{-2}}$$

What is the overall order of the reaction?

COMEDK 2023 Evening Shift
31

Match the details given in Column I with those given in Column II

S.No. Column I S.No. Column II
A For complex reactions order is determined by P Rate of reaction.
B For Zero order reaction unit of $\mathrm{k}$ is same as that of Q Slope $$=k/2.303$$
C Mathematical expression which gives relationship between rate of reaction and concentrations of reactants is called R Slowest rate determining step.
D For a first order reaction plot of $$\mathrm{\log \left[R_0\right] /[R]}$$ vs time gives S Rate law.

COMEDK 2023 Evening Shift
32

Given below are graphs showing the variation in velocity constant with temperature on Kelvin scale. Identify the graph which represents Arrhenius equation.

COMEDK 2023 Evening Shift Chemistry - Chemical Kinetics Question 26 English

COMEDK 2023 Evening Shift
33

The rate constant for a First order reaction at $$560 \mathrm{~K}$$ is $$1.5 \times 10^{-6}$$ per second. If the reaction is allowed to take place for 20 hours, what percentage of the initial concentration would have converted to products?

COMEDK 2023 Evening Shift
34

A newly prepared radioactive nuclide has a decay constant of 6.93 s$$^{-1}$$. What is the half-life of the nuclide?

COMEDK 2022
35

Which of the following statement is incorrect about activation energy?

COMEDK 2022
36

For the reaction 2N$$_2$$O$$_5$$ $$\to$$ 4NO$$_2$$ + O$$_2$$.

If initial pressure is 100 atm and rate constant $$k$$ is 3.38 $$\times$$ 10$$^{-5}$$ s$$^{-1}$$. after 20 min the final pressure of N$$_2$$O$$_5$$ will be

COMEDK 2022
37

Determine the specific rate constant of the reaction. If the half-life period of a first order reaction is 1402 s.

COMEDK 2021
38

Rate constant (K) of a reaction has least value at

COMEDK 2021
39

For the reaction 2N$$_2$$O$$_5$$ $$\to$$ 4NO$$_2$$ + O$$_2$$, rate constant $$k$$ is 4.48 $$\times$$ 10$$^{-5}$$ s$$^{-1}$$ and the initial pressure is 600 atm. After 10 min, determine the final pressure of N$$_2$$O$$_5$$.

COMEDK 2021
40

Which one of the following is a second order reaction?

COMEDK 2020
EXAM MAP
Medical
NEETAIIMS
Graduate Aptitude Test in Engineering
GATE CSEGATE ECEGATE EEGATE MEGATE CEGATE PIGATE IN
Civil Services
UPSC Civil Service
Defence
NDA
Staff Selection Commission
SSC CGL Tier I
CBSE
Class 12