Question

In a nuclear chain fission reaction, every neutron causing fission results in the production of
(A) $\;2.5$ times more neutrons
(B) Almost less than the one neutron
(C) Exactly one neutron
(D) None of the above

Answer 1

Hint : In nuclear reactions, when the neutrons are bombarded, the radioactive Uranium splits into two different elements and gives out a different number of neutrons. Hence, we can find the average of the neutrons emitted in different nuclear reactions.

Complete Step By Step Answer:
Scientist Chadwick proved that as the neutron is chargeless, it does not experience any attractions or repulsions, and hence it can penetrate the nucleus deeply.
It has been experimentally proven that if a neutron is bombarded on uranium, the uranium breaks down into almost equal mass elements, a different number of neutrons are emitted and an immense amount of energy is released.
This process of production of energy by bombarding neutrons on the nucleus is known as nuclear fission.
By the fission of uranium, different kinds of elements and different number of neutrons are obtained, which are as follows;
${}_{92}^{235}U + {}_0^1n \to {}_{92}^{236}U \to {}_{56}^{144}Ba + {}_{36}^{89}Kr + 3{}_0^1n + Q$
${}_{92}^{235}U + {}_0^1n \to {}_{92}^{236}U \to {}_{51}^{133}Sb + {}_{41}^{99}Nb + 4{}_0^1n + Q$
${}_{92}^{235}U + {}_0^1n \to {}_{92}^{236}U \to {}_{54}^{140}Xe + {}_{38}^{94}Sr + 2{}_0^1n + Q$
Later it was suggested that if the neutrons obtained as the product of the nuclear fission are further used for nuclear fission, a more immense amount of energy can be produced.
Hence, the process of using the neutrons obtained in the product of nuclear fission for further continuing the nuclear fission reaction is known as the nuclear chain fission reaction.
Hence, by bombarding one neutron, we can get $3$ , $4$ , or $2$ neutrons which can be further used for nuclear fission of $3$ , $4$ , or $2$ Uranium nucleus.
As we can see that the number of released neutrons is different, to write a general value for the released neutrons per reaction we will take the average of all the different numbers of neutrons released which turns out to be equal to $\;2.5$ .
Hence, the correct answer is Option $(A)$ .

Note :
We know that there does not exist a term called half neutron. But still, here we have taken the number of neutrons to be $\;2.5$ . This does not mean that a half neutron is produced in every reaction and the product of every reaction is the same. But as the products are different in each case, for the ease of calculations, we consider the number of neutrons released per reaction as $\;2.5$ .