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Percentage of a radioactive element decayed after 20 sec when half-life is 4 sec

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Important Questions on Chemical Kinetics

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

Draw the curve showing the variation of binding energy per nucleon as a function of mass number

A

. Explain the stability of nucleus from the curve

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

Define the term ‘decay constant’ of a radioactive sample. The rate of disintegration of a given radioactive nucleus is

10000

disintegrations and

5, 000

disintegrations after

20 h o u r

. and

30 h o u r

. respectively from start. Calculate the half-life and the initial number of nuclei at

t = 0

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

What is meant by half life of a radioactive substance? Write its relation with decay constant.

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

Decomposition of

X

exhibits a rate constant of

0 .05 μg / year

. How many years are required for the decomposition of

5 μg

X

into

2 .5 μg

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

Consider, the radioactive disintegration

{}_{82}A^{210} \to B \to C \to {}_{82}D^{206}

The sequence of emission can be

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

The rate of a first-order reaction is

0.04 m o l l^{- 1} s^{- 1}

10

second and

0.03 m o l l^{- 1} s^{- 1}

20

seconds after initiation of the reaction. The half-life period of the reaction is:

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

Predict the element resulting from two

α

decay, two consecutive

β

decay and one

γ

decay of

Th - 232

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

The rate constant for a first order reaction is

7 .0 \times 10^{- 4} s^{- 1} .

If initial concentration of the reactant is

0.080 M

, what is the half-life of the reaction?

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

The decay constant which is the reciprocal of the time duration for which the number of the atoms of radioactive substance falls to

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

If the quantity of a radioactive element is doubled, the rate of disintegration will

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

The rate constant of the reaction

A ⟶ B

0.6 \times 10^{- 3}

mole per liter per second. If the initial concentration of A is 5 M, then the concentration of B after 20 minutes is:

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

A bacterial infection in an internal wound grows as

N^{'} (t) = N_{0} e x p (t)

, where the time

t

is in hours. A dose of antibiotic, taken orally, needs 1 hour to reach the wound. Once it reaches there, the bacterial population goes down as

\frac{d N}{d t} = - 5 N^{2}

. What will be the plot of

\frac{N_{0}}{N}

t

after

1

hour?

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

The reaction

2 N_{2} O_{5} (g) \to 4 N O_{2} (g) + O_{2} (g)

follows first order kinetics. The pressure of a vessel containing only

N_{2} O_{5}

was found to increase from 50 mm Hg to 87.5 mm Hg in 30 min. The pressure exerted by the gases after 60 min. Will be (Assume temperature remains constant) :

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

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 both of them to be same? ________min.

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

When initial concentration of a reactant is doubled in a reaction, its half-life period is not affected. The order of the reaction is:

MEDIUM

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

For a zero - order reaction with rate constant k, the slope of the plot reactant concentration against time is

EASY

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

Which among the following reactions can be an example of pseudo first order reaction?

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

A radioactive sample is emitting

64

times radiations than non-hazardous limit. If its half life is

2 h

, after what time it become non hazardous?

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

{}_{92}^{238}U

is known to undergo radioactive decay to form

{}_{82}^{206}{Pb}

by emitting alpha and beta particles. A rock initially contained

68 \times 10^{- 6} g

{}_{92}^{238}U

. If the number of alpha particles that it would emit during its radioactive decay of

{}_{92}^{238}U

{}_{82}^{206}{Pb}

in three half-lives is

Z \times 10^{18}

, then what is the value of

Z

HARD

Chemistry>Physical Chemistry>Chemical Kinetics>Integrated Rate Equations of Chemical Reaction

In the nuclear transmutation

_{4}^{9} Be + X ⟶_{4}^{8} Be + Y

, identify

(X, Y)

Percentage of a radioactive element decayed after 20 sec when half-life is 4 sec

Important Questions on Chemical Kinetics

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