Question

Nuclear fission can be explained by

A. proton-proton cycle
B. liquid drop model of nucleus  
C. independent of nuclear particle model
D. nuclear shell model
Answer :   liquid drop model of nucleus
Solution :
Neil Bohr and J.A. Wheeler explained the nuclear fission on the basis of liquid drop model of the nucleus. The $$_{92}{U^{235}}$$  nucleus behaves like a liquid drop and owing to surface tension is perfectly spherical in shape. When the neutron strikes the nucleus, some energy called the excitation energy is imparted to the nucleus.
Atoms or Nuclear Fission and Fusion mcq solution image
The phenomenon of surface tension tries to keep the nucleus spherical in shape, whereas the excitation energy tries to deform it. Due to the struggle between the surface tension and the excitation energy, the oscillations are set up inside the compound nucleus.
As a result, the nucleus gets deformed from spherical shape to ellipsoidal and then to a dumb bell as shown, till the Coulomb’s repulsive force between protons succeeds in tearing the two bells apart.

Releted MCQ Question on
Modern Physics >> Atoms or Nuclear Fission and Fusion

Releted Question 1

The equation
$$4_1^1{H^ + } \to _2^4H{e^{2 + }} + 2{e^ - } + 26MeV$$       represents

A. $$\beta $$ -decay
B. $$\gamma $$ -decay
C. fusion
D. fission
Releted Question 2

Fast neutrons can easily be slowed down by

A. the use of lead shielding
B. passing them through water
C. elastic collisions with heavy nuclei
D. applying a strong electric field
Releted Question 3

In the nuclear fusion reaction
$$_1^2H + _1^3H \to _2^4He + n$$
given that the repulsive potential energy between the two nuclei is $$ \sim 7.7 \times {10^{ - 14}}J,$$    the temperature at which the gases must be heated to initiate the reaction is nearly
[Boltzmann’s Constant $$k = 1.38 \times {10^{ - 23}}J/K$$    ]

A. $${10^7}K$$
B. $${10^5}K$$
C. $${10^3}K$$
D. $${10^9}K$$
Releted Question 4

The binding energy per nucleon of deuteron $$\left( {_1^2H} \right)$$ and helium nucleus $$\left( {_2^4He} \right)$$  is $$1.1\,MeV$$  and $$7\,MeV$$  respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is

A. $$23.6\,MeV$$
B. $$26.9\,MeV$$
C. $$13.9\,MeV$$
D. $$19.2\,MeV$$

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