Question

${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}}$ nucleus absorbs a neutron and disintegrates into ${}_{{\text{54}}}{\text{X}}{{\text{e}}^{{\text{139}}}}$, ${}_{{\text{38}}}{\text{S}}{{\text{r}}^{{\text{94}}}}$ and x. what will be the product x?
A. 3 neutrons
B. 2 neutrons
C. 2 $\alpha$-particles
D. 2 $\beta$-particles

Answer 1

We are given that the uranium nucleus ${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}}$ reacts with a neutron and undergoes a nuclear fission reaction to produce ${}_{{\text{54}}}{\text{X}}{{\text{e}}^{{\text{139}}}}$, ${}_{{\text{38}}}{\text{S}}{{\text{r}}^{{\text{94}}}}$ and a by-product x. We can find the product x by writing a balanced nuclear reaction.

Complete step by step solution:
We are given that ${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}}$ absorbs a neutron and disintegrates into two lighter nuclei ${}_{{\text{54}}}{\text{X}}{{\text{e}}^{{\text{139}}}}$ and ${}_{{\text{38}}}{\text{S}}{{\text{r}}^{{\text{94}}}}$ along with product x. Thus, we can say that a heavy unstable nucleus absorbs a neutron and energy and disintegrates into lighter nuclei. This is known as nuclear fission.
In nuclear fission, an unstable nucleus disintegrates and undergoes fission and splits into a lighter nuclei.
The unstable nucleus undergoes fission when it is bombarded by neutrons. In a controlled nuclear fission, the number of neutrons can be restricted by slowing down the neutrons.
When ${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}}$ nucleus absorbs a neutron i.e. when ${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}}$ nucleus undergoes a controlled nuclear fission it disintegrates into two lighter nuclei ${}_{{\text{54}}}{\text{X}}{{\text{e}}^{{\text{139}}}}$ and ${}_{{\text{38}}}{\text{S}}{{\text{r}}^{{\text{94}}}}$ along with some neutrons.
The nuclear reaction is as follows:
${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}} + {}_{\text{0}}{{\text{n}}^{\text{1}}} \to {}_{{\text{54}}}{\text{X}}{{\text{e}}^{{\text{139}}}} + {}_{{\text{38}}}{\text{S}}{{\text{r}}^{{\text{94}}}} + x$
We can balance the nuclear reaction by equating the number of protons and neutrons on both sides of the reaction. Thus, the balanced nuclear reaction is as follows:
${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}} + {}_{\text{0}}{{\text{n}}^{\text{1}}} \to {}_{{\text{54}}}{\text{X}}{{\text{e}}^{{\text{139}}}} + {}_{{\text{38}}}{\text{S}}{{\text{r}}^{{\text{94}}}} + 2{}_{\text{0}}{{\text{n}}^{\text{1}}}$
Thus, two neutrons are produced in this reaction.
Thus, ${}_{{\text{92}}}{{\text{U}}^{{\text{235}}}}$ nucleus absorbs a neutron and disintegrates into ${}_{{\text{54}}}{\text{X}}{{\text{e}}^{{\text{139}}}}$, ${}_{{\text{38}}}{\text{S}}{{\text{r}}^{{\text{94}}}}$ and 2 neutrons.

**Thus, the correct option is (B) 2 neutrons.

Note: **
In a nuclear fission, a heavy nucleus disintegrates into lighter nuclei. Large amount of energy is released during nuclear fission. Nuclear fission occurs by itself and no additional energy is required for a nuclear fission to occur.