In the decay sequence: U 92 238 → - x 1 Th 90 234 → - x 2 Pa 91 234 → - x 3 Z 234 → - x 4 Th 90 234 x 1 , x 2 , x 3 and x 4 are the particles/ radiation emitted by the respective isotopes. The correct option(s) is/are:

x 1 will deflect towards the negatively charged plate.

EASY

Earn 100

What do you mean by radioactive substances?

Important Questions on Thermionic Emission and Radioactivity

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^{227} A c

has a half-life of 22 years with respect to radioactive decay. The decay follows two parallel paths:

^{227} Ac \to^{227} T h

and

^{227} Ac \to^{223} F r

. If the percentage of the two daughter nuclides are

2.0

and

98.0

, respectively the decay constant (in

y e a r^{- 1}

) for

^{227} Ac \to^{227} T h

path is closest to

MEDIUM

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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?

EASY

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

Consider, the radioactive disintegration

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

The sequence of emission can be

MEDIUM

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

The ratio of the binding energies of three nuclei is

1 : 4 : 9

. If the ratio of their nuclear radii is

1 : 2 : 3

, the nuclei in the decreasing order of the stability can be arranged as

EASY

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

Write any three properties of $β -$ rays.

MEDIUM

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

A nucleus

X

captures a

β

particle and then emits a neutron and

γ

ray to form

Y . X

and

Y

are:-

HARD

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

{}_{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

MEDIUM

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

{}_{93}^{239}{Np}

is a

β

-emitter, but the product is also radioactive and give

{}^{235}U

. Which particle(s) is/are emitted by the product?

MEDIUM

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

Compare the charge and ionising power of $α and γ$ rays. Mention one use of radioactivity.

EASY

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

In the radioactive disintegration series

_{90}^{232} T h \to_{82}^{208} P b,

involving

α

and

β

decay, the total number of

α

and

β

particles emitted are

EASY

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

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

EASY

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

Select the correct option

MEDIUM

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

In the radioactive decay process

Question Image

1. A and B are isobars

2. A and D are isotopes

3. C and D are isobars

4. A and C are isotopes

EASY

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

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

HARD

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

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

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

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

MEDIUM

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

The particles emitted during the sequential radioactive decay of

{}^{238}U_{92}

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

are

HARD

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

In the nuclear transmutation

_{4}^{9} Be + X ⟶_{4}^{8} Be + Y

, identify

(X, Y)

EASY

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

The ionisation power is maximum for:

MEDIUM

Science>Physics>Thermionic Emission and Radioactivity>Radioactivity

In the decay sequence:

${}_{92}^{238}U \overset{- x_{1}}{\to} {}_{90}^{234}{Th} \overset{- x_{2}}{\to} {}_{91}^{234}{Pa} \overset{- x_{3}}{\to} {}^{234}Z \overset{- x_{4}}{\to} {}_{90}^{234}{Th}$

$x_{1}, x_{2}, x_{3}$ and $x_{4}$ are the particles/ radiation emitted by the respective isotopes. The correct option(s) is/are:

What do you mean by radioactive substances?

Important Questions on Thermionic Emission and Radioactivity

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