Chemical Kinetics · Chemistry · KCET

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MCQ (Single Correct Answer)

1

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
2

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
3

Which one of the following does not represent Arrhenius equation?

KCET 2024
4

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

KCET 2023
5

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
6

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
7

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

KCET 2022
8

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
9

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
10

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
11

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
12

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
13

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
14

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

KCET 2021
15

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
16

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
17

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
18

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
19

Which is a wrong statement?

KCET 2019
20

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
21
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
22
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
23
The value of rate constant of a pseudo first order reaction
KCET 2018
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