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What is the name of India's first nuclear test site?

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Important Questions on Nuclei

HARD

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

Define the term ‘Half-life’ of a radioactive substance. Two different radioactive substances have half-lives

T_{1}

and

T_{2}

and number of undecayed atoms at an instant,

N_{1}

and

N_{2}

, respectively. Find the ratio of their activities at that instant.

HARD

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

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

HARD

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

The nucleus ${}_{92}^{235}Y$ , initially at rest, decays into ${}_{90}^{231}X$ by emitting an $α -$ particle.

${}_{92}^{235}Y \to {}_{90}^{231}X + {}_{2}^{4}{He} +$ energy

The binding energy per nucleon of the parent nucleus, the daughter nucleus and $α -$ particles are $7.8 Mev, 7.835 Mev$ and $7.07 Mev$ , respectively. Assuming the daughter nucleus to be formed in the excited state and neglecting its share in the energy of the reaction, find the speed of the emitted $α -$ particle. (Mass of $α -$ particle $= 6.68 \times 10^{- 27} kg$ )

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

In which process neutron is converted into proton?

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

A radioactive element has a rate of disintegration

10, 000

disintegrations per minute at a particular instant. After four minutes it becomes

2500

disintegrations per minute. The decay constant per minute is

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

What will be the value of neutron multiplication factor for controlled chain reactions?

MEDIUM

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

β

-decay, the parent and daughter nuclei have the same number of _____.

HARD

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

Explain the principle and working of a nuclear reactor with the help of a labelled diagram.

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

A decay chain of the nucleus

{}_{92}^{238}U

involves eight

α

-decays and six

β

-decays. The final nucleus at the end of the process will be

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

Radioactive material

A

has decay constant

8 λ

and material

B

has decay constant

λ

. Initially they have the same number of nuclei. After what time, the ratio of number of nuclei of material

A

to that

B

will be

\frac{1}{e} ?

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

A sample of radioactive material

A

, that has an activity of

10 mCi (1 Ci = 3.7 \times 10^{10} d e c a y s^{- 1})

has twice the number of nuclei as another sample of a different radioactive material

B

which has an activity of

20 mCi

. The correct choices for half-lives of

A

and

B

would then be, respectively:

HARD

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

Explain the processes of nuclear fission and nuclear fusion by using the plot of binding energy per nucleon

(B E / A)

versus the mass number

A

MEDIUM

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

2 M e V

neutron is emitted in a fission reactor. If it looses half of its kinetic energy in each collision with a moderator atom, how many collisions must it undergo to achieve thermal energy of

0.039 e V

HARD

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

A radioactive isotope has a half-life of

10

years. How long will it take for the activity to reduce to

3.125 %

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

The ratio of mass densities of nuclei of

^{40} C a

and

^{16} O

is close to:

MEDIUM

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

Expressed sequence tags (ESTs) refers to:

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

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,

HARD

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

A plot of the number of neutrons

(N)

against the number of protons

(P)

of the stable nuclei exhibits upwards deviation from linearity for atomic number,

Z > 20

. For an unstable nucleus having

\frac{N}{P}

ratio less than

1

, the possible mode(s) of decay is (are):

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

Four nuclei of an element undergo fusion to form a heavier nucleus, with release of energy. Which of the two the parent or the daughter nucleus would have higher binding energy per nucleon ?

EASY

Physics>Modern Physics>Nuclei>Mass-energy and Nuclear Binding Energy

m, m_{n}

and

m_{p}

are the masses of

{}_{Z}X^{A}

nucleus, neutron and proton, respectively, then,

What is the name of India's first nuclear test site?

Important Questions on Nuclei

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