Chemical Kinetics · Chemistry · KCET

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MCQ (Single Correct Answer)

1
The activation energy for the reaction $X \rightarrow Y$ is $150\text{ kJ mol}^{-1}$. The change in enthalpy for the above reaction is $-135\text{ kJ mol}^{-1}$. Then the activation energy for $Y \rightarrow X$ is
KCET 2026
2
For a 1st order change $R \rightarrow P$, the concentration of Reactant R changes from $0.1$ M to $0.025$ M in $40$ minutes. The rate of reaction when the concentration of R is $0.01$ M is ____
KCET 2026
3
For a reaction having three steps, the overall rate constant is $k = \dfrac{k_1 k_2}{k_3}$. The values of $E_{a_1}, E_{a_2}$ and $E_{a_3}$ (activation energies stepwise) are $40$, $50$ and $60$ kJ mol$^{-1}$ respectively. Then the overall $E_a$ (activation energy) of the reaction is ____
KCET 2026
4
Which one of the following graph is not applicable for a 1st order reaction ($R \rightarrow P$)?
KCET 2026
5

Catalysts are used to increase the rate of a chemical reaction. Because it

KCET 2025
6

Half-life of a first order reaction is 20 seconds and initial concentration of reactant is 0.2 M . The concentration of reactant left after 80 seconds is

KCET 2025
7

$$ \text { In the given graph, } \mathrm{E}_{\mathrm{a}} \text { for the reverse reaction will be } $$

KCET 2025 Chemistry - Chemical Kinetics Question 5 English
KCET 2025
8

For the reaction $2 \mathrm{~N}_2 \mathrm{O}_{5(\mathrm{~g})} \rightarrow 4 \mathrm{NO}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})}$ initial concentration of $\mathrm{N}_2 \mathrm{O}_5$ is $2.0 \mathrm{molL}^{-1}$ and after 300 min , it is reduced to $1.4 \mathrm{molL}^{-1}$. The rate of production of $\mathrm{NO}_2\left(\mathrm{in} \mathrm{molL}^{-1} \mathrm{~min}^{-1}\right)$ is

KCET 2025
9

For the reaction, $A \rightleftharpoons B, E_a=50 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\Delta H=-20 \mathrm{~kJ} \mathrm{~mol}^{-1}$. When a catalyst is added $E_a$ decreases by $10 \mathrm{~kJ} \mathrm{~mol}^{-1}$. What is the $E_a$ for the backward reaction in the presence of catalyst?

KCET 2024
10

For the reaction, $\mathrm{PCl}_5 \longrightarrow \mathrm{PCl}_3+\mathrm{Cl}_2$, rate and rate constant are $1.02 \times 10^{-4} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$ and $3.4 \times 10^{-5} \mathrm{~s}^{-1}$ respectively at a given instant. The molar concentration of $\mathrm{PCl}_5$ at that instant is

KCET 2024
11

Which one of the following does not represent Arrhenius equation?

KCET 2024
12

In which one of the following reactions, rate constant has the unit $$\mathrm{mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$$ ?

KCET 2023
13

For a reaction, the value of rate constant at $$300 \mathrm{~K}$$ is $$6.0 \times 10^5 \mathrm{~s}^{-1}$$. The value of Arrhenius factor $$A$$ at infinitely high temperature is

KCET 2023
14

The rate constant $$k_1$$ and $$k_2$$ for two different reactions are $$10^{16} \times e^{-2000 / T}$$ and $$10^{15} \times e^{-1000 / T}$$ respectively. The temperature at which $$k_1=k_2$$ is

KCET 2023
15

For $$n$$th order of reaction, half-life period is directly proportional to

KCET 2022
16

Half-life of a reaction is found to be inversely proportional to the fifth power of its initial concentration, the order of reaction is

KCET 2022
17

A first order reaction is half completed in $$45 \mathrm{~min}$$. How long does it need $$99.9 \%$$ of the reaction to be completed?

KCET 2022
18

The rate of the reaction, $$\mathrm{CH}_3 \mathrm{COOC}_2 \mathrm{H}_5+\mathrm{NaOH} \longrightarrow \mathrm{CH}_3 \mathrm{COONa}+\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$$ is given by the equation, rate $$=k\left[\mathrm{CH}_3 \mathrm{COOC}_2 \mathrm{H}_5\right][\mathrm{NaOH}]$$. If concentration is expressed in $$\mathrm{mol} \mathrm{L}^{-1}$$, the unit of $$k$$ is

KCET 2022
19

For a reaction, $$A+2 B \rightarrow$$ Products, when concentration of $$B$$ alone is increased half-life remains the same. If concentration of $$A$$ alone is doubled, rate remains the same. The unit of rate constant for the reaction is

KCET 2021
20

If the rate constant for a first order reaction is $$k$$, the time $$(t)$$ required for the completion of $$99 \%$$ of the reaction is given by

KCET 2021
21

The rate of a gaseous reaction is given by the expression $$k[A][B]^2$$. If the volume of vessel is reduced to one half of the initial volume, the reaction rate as compared to original rate is

KCET 2021
22

Higher order $$(>3)$$ reactions are rare due to

KCET 2021
23

The time required for $$60 \%$$ completion of a first order reaction is $$50 \mathrm{~min}$$. The time required for $$93.6 \%$$ completion of the same reaction will be

KCET 2020
24

For an elementary reaction $$2 A+3 B \rightarrow 4 C+D$$ the rate of appearance of $C$ at time '$$T$$' is $$2.8 \times 10^{-3} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~S}^{-1}$$. Rate of disappearance of $$B$$ at '$$t$$' $t$ will be

KCET 2020
25

The rate constant of a reaction is given by $$k=P Z e^{-E_a / R T}$$ under standard notation. In order to speed up the reaction, which of the following factors has to be decreased?

KCET 2020
26

The plot of $$t_{1 / 2} \mathrm{~v} / \mathrm{s}~[R]_0$$ for a reaction is a straight-line parallel to $$X$$-axis. The unit for the rate constant of this reaction is

KCET 2019
27

Which is a wrong statement?

KCET 2019
28

1L of $$2 \mathrm{M~CH}_3 \mathrm{COOH}$$ is mixed with 1L of $$3 \mathrm{M} \mathrm{~C}_2 \mathrm{H}_5 \mathrm{OH}$$ to form an ester. The rate of the reaction with respect to the initial rate when each solution is diluted with an equal volume of water will be

KCET 2019
29
For the reaction, $2 \mathrm{SO}_2+\mathrm{O}_2 \rightleftharpoons 2 \mathrm{SO}_3$, the rate of disappearance of $\mathrm{O}_2$ is $2 \times 10^{-4} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$. The rate of appearance of $\mathrm{SO}_3$ is
KCET 2018
30
The temperature coefficient of a reaction is 2. When the temperature is increased from $30^{\circ} \mathrm{C}$ to $90^{\circ} \mathrm{C}$, the rate of saction is increased by
KCET 2018
31
The value of rate constant of a pseudo first order reaction
KCET 2018
32
For a reaction $\frac{1}{2} A \rightarrow 2 B$ rate of disappearance of $A$ is related to rate of appearance of $B$ by the expression
KCET 2017
33
Which of the following statement is incorrect?
KCET 2017
34
Which of the following statement is in accordance with the Arrhenius equations?
KCET 2017