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# Class 10 FRANK Solutions Physics Chapter 6.2 - Nuclear Fission and Fusion

## Nuclear Fission and Fusion Exercise 265

### Solution 1

No. of neutrons = Atomic mass - No. of protons

Thus,

n = A - Z

n = 238 - 92 = 146

### Solution 2

Neutrons are uncharged particles in the nucleus of an atom.

### Solution 3

The process of splitting of heavy nuclei into lighter nuclei when bombarded with low energy neutrons is called nuclear fission.

Nuclear fission can be controlled or uncontrolled.

### Solution 4

In controlled fission reaction, out of 3 neutrons released in nuclear fission, 2 neutrons are absorbed and one neutron is available to cause fission so that nuclear reaction takes place at a steady rate and slows down.

### Solution 5

 Nuclear Fission Nuclear fusion In fission reactions, a heavy nucleus is split into two nuclei with smaller mass numbers. In fusion reactions, two light nuclei are combined to form a heavier, more stable nucleus. The amount of energy required to split two atoms in a fission reaction is less as compared to fusion reaction. A tremendous large amount of energy is required to bring two or more protons close enough to overcome their electrostatic force of repulsion. Tremendous large amount of energy is released by fission reactions; but lower than the energy released by nuclear fusion. The energy released by fusion reactions is three to four times greater than the energy released by fission reaction.

### Solution 6

The process in which the two lighter nuclei fuse to form a stable heavier nucleus with the liberation of large amount of energy is called nuclear fusion.

### Solution 7

The sun generates energy from a process called nuclear fusion.

Hydrogen nuclei in the interior of the Sun under high temperature and pressure fuse together to form nuclei.

### Solution 8

 Controlled nuclear fission Uncontrolled nuclear fission A controlled chain reaction is a chain of nuclear reactions that take place subsequently under controlled conditions. An uncontrolled chain reaction is a chain of nuclear reactions that take place subsequently, but not under controlled conditions. In a controlled nuclear fission, out of 3 neutrons released, 2 neutrons are absorbed and the one neutron is available to induce fission process so that nuclear reaction takes place at steady rate and slows down. In an uncontrolled process, all the neutrons are allowed to cause a fission and the reaction continues exponentially. This is a chain reaction.