Tritium is an isotope of hydrogen whose nucleus Triton contains 2 neutrons and 1 proton. Free neutrons decay into p + e ¯ + V ¯ . If one of the neutrons in Triton decays, it would transform into He 3 nucleus. This does not happen. This is because

Triton energy is less than that of a He 3 nucleus.

the electron created in the beta decay process cannot remain in the nucleus.

both the neutrons In triton have to decay simultaneously resulting in a nucleus with 3 protons, which is not a He 3 nucleus.

because free neutrons decay due to external perturbations which is absent in a triton nucleus.

E M B I B E

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>LA>Q 13.26

EASY

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IMPORTANT

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Nuclei with magic no. of proton $Z = 2, 8, 20, 28, 50, 52$ and magic no. of neutrons $N = 2, 8, 20, 28, 50, 82 and 126$ are found to be very stable,

What does the existance of magic number indicate?

Important Questions on Nuclei

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IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.1

Suppose we consider a large number of containers each containing initially

10000

atoms of a radioactive material with a half life of

1

year. After

1

year.

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IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.2

The gravitational force between a $H$ -atom and another particle of mass m will be given by Newton’s law:

$F = G \frac{M \cdot m}{r^{2}}$ where $r$ is in $km$ and

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NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.3

When a nucleus in an atom undergoes a radioactive decay, the electronic energy levels of the atom

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IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.4

M_{x}

and

M_{y}

denote the atomic masses of the parent and the daughter nuclei respectively in a radioactive decay. The

Q

-value for a

β^{-}

decay is

Q_{1}

and that for a

β^{+}

decay is

Q_{2}

. If

m_{e}

denotes the mass of an electron, then which of the following statements is correct?

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IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.5

Tritium is an isotope of hydrogen whose nucleus Triton contains

2

neutrons and

1

proton. Free neutrons decay into

p + \bar{e} + \bar{V}

. If one of the neutrons in Triton decays, it would transform into

{He}^{3}

nucleus. This does not happen. This is because

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IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.6

Heavy stable nucleus have more neutrons than protons. This is because of the fact that

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IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.7

In a nuclear reactor, moderators slow down the neutrons which come out in a fission process. The moderator used light nuclei. Heavy nuclei will not serve the purpose because

EASY

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IMPORTANT

NCERT Exemplar Physics - Class 12>Chapter 13 - Nuclei>MCQ>Q 13.8

Fusion processes, like combining two deuterons to form a

He

nucleus are impossible at ordinary temperatures and pressure. The reasons for this can be traced to the fact:

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Nuclei with magic no. of proton Z=2,8,20,28,50,52 and magic no. of neutrons N=2,8,20,28,50,82 and 126 are found to be very stable, What does the existance of magic number indicate?

Important Questions on Nuclei

Learn and Prepare for any exam you want !

Nuclei with magic no. of proton $Z = 2, 8, 20, 28, 50, 52$ and magic no. of neutrons $N = 2, 8, 20, 28, 50, 82 and 126$ are found to be very stable,

What does the existance of magic number indicate?