A neutron in the nucleus decays emitting an electron.

A proton in the nucleus decays emitting an electron.

An electron which is already present within the nucleus is ejected.

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What is the difference between natural and artificial radioactivity?

Important Questions on Nuclear Physics

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Physics>Modern Physics>Nuclear Physics>Radioactivity

The half-life period of a radioactive element $X$ is same as the mean-life time of another radioactive element

Y

.
Initially, they have the same number of atoms. Then,

MEDIUM

Physics>Modern Physics>Nuclear Physics>Radioactivity

The activity of a radioactive sample falls from

700 s^{- 1}

500 s^{- 1}

30

minutes. Its half life is close to:

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Physics>Modern Physics>Nuclear Physics>Radioactivity

The end product of decay of

_{90} {Th}^{232}

_{82} {Pb}^{208}

. The number of

α

and

β

particles emitted are respectively

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Physics>Modern Physics>Nuclear Physics>Radioactivity

Radioactive element decays to form a stable nuclide, then the rate of decay of reactant is shown by

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Physics>Modern Physics>Nuclear Physics>Radioactivity

A nucleus of uranium decays at rest into nuclei of thorium and helium. Then:

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Physics>Modern Physics>Nuclear Physics>Radioactivity

Activities of three radioactive substances $A, B$ and $C$ are represented by the curves $A, B$ and $C,$ in the figure. Then their half-lives $T_{\frac{1}{2}} (A) : T_{\frac{1}{2}} (B) : T_{\frac{1}{2}} (C)$ are in the ratio:

Question Image

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Physics>Modern Physics>Nuclear Physics>Radioactivity

Which one of the following nuclei has shorter mean life?

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Physics>Modern Physics>Nuclear Physics>Radioactivity

During a

β

- decay

HARD

Physics>Modern Physics>Nuclear Physics>Radioactivity

At some instant, a radioactive sample

S_{1}

having an activity

5 μ Ci

has twice the number of nuclei as another sample

S_{2}

which has an activity of

10 μ Ci

. The ratio of half lives of

S_{1} a n d S_{2}

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Physics>Modern Physics>Nuclear Physics>Radioactivity

A radioactive nucleus

A

with a half-life

T

, decays into a nucleus

B

. At

t = 0

, there is no nucleus

B

. At some time

t

, the ratio of the number of

B

to that of

A

0.3

. Then,

t

is given by:

(Consider \log_{e} (x) = \log (x))

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Physics>Modern Physics>Nuclear Physics>Radioactivity

The half-life period and the mean life period of a radioactive element are denoted respectively by

T_{h}

and

T_{m}

. Then

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Physics>Modern Physics>Nuclear Physics>Radioactivity

At a given instant, say

t = 0,

two radioactive substance

A

and

B

have equal activities. The ratio

\frac{R_{B}}{R_{A}}

of their activities after time

t

itself decays with time

t

e^{- 3 t} .

If the half-life of

A

l n 2,

the half-life of

B

is:

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Physics>Modern Physics>Nuclear Physics>Radioactivity

The activity of a radioactive sample is measured as

N_{0}

counts per minute at

t = 0

and

\frac{N_{0}}{e}

counts per minute at

t = 5 \min

. The time (in minutes) at which the activity reduces to half its value is

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Physics>Modern Physics>Nuclear Physics>Radioactivity

In a radioactive material, a fraction of active material remaining after the time

t is \frac{9}{16}

. The fraction that was remaining after the time

\frac{t}{2}

is :

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Physics>Modern Physics>Nuclear Physics>Radioactivity

{}_{90}^{232}{Th}

emits

6 α

and

4 β

particles and gets converted into a lead. The mass number and atomic number of lead is _____

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Physics>Modern Physics>Nuclear Physics>Radioactivity

Assertion (A) : Neutrino is chargeless and possesses spin.

Reason $(R) :$ Neutrino exists inside the nucleus.

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Physics>Modern Physics>Nuclear Physics>Radioactivity

A radio-active element has a half-life of

15 years

. What fraction of this element will decay in

30

years

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Physics>Modern Physics>Nuclear Physics>Radioactivity

Half lives of two radioactive nuclei

A

and

B

are 10 minutes and 20 minutes, respectively. If, initially a sample has equal number of nuclei, then after 60 minutes, the ratio of decayed numbers of nuclei A and B will be:

HARD

Physics>Modern Physics>Nuclear Physics>Radioactivity

In a radioactive decay chain,

_{90}^{232} Th

nucleus decays to

_{82}^{212} Pb

nucleus. Let

N_{α} and N_{β}

be the number of

α and β^{-}

particles, respectively, emitted in this decay process. Which of the following statements is (are) true?

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Physics>Modern Physics>Nuclear Physics>Radioactivity

An accident in a nuclear laboratory resulted in deposition of a certain amount of radioactive material of half-life

18

days inside the laboratory. Tests revealed that the radiation was

64

times more than the permissible level required for safe operation of the laboratory. What is the minimum number of days after which the laboratory can be considered safe for use?

What is the difference between natural and artificial radioactivity?

Important Questions on Nuclear Physics

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