Question

${{D}_{2}}O$ is used more in:
(A)- chemical industry
(B)- nuclear moderator
(C)- pharmaceutical preparation
(D)- insecticide preparations

Answer 1

The heavy water being a heavier isotope and showing lower absorption of the neutrons, makes them effective in the moderation of its speed. So, we can choose from the option based on its chemical property.

Complete step by step answer:
The deuterium oxide is also known as the heavy water. Due to the presence of the heavier isotope of hydrogen present in it. So, it can also be represented as $^{2}{{H}_{2}}O$ , where the deuterium has one proton and one neutron in it.
This increased mass of the deuterium compared to the normal proton in water leads to a change in its chemical properties, with its bonding related to the reduced mass.
The heavy water is used in the nuclear reactors where the fission reaction of the fissile uranium-235 takes place producing fast neutrons.
So, in order to slow down the speed of the neutrons to allow it to be absorbed effectively by the other nuclei and cause further splitting to carry out the chain reaction. The heavy water is used as the moderator of the neutrons.
The neutron absorption cross-section is slower in the heavy water and due to the small size of its nucleus as the neutron. The elastic collision is possible and more is the decrease in the speed of the neutrons in the reactor. Thus, making them efficient neutron moderators.
So, the correct answer is “Option B”.

Note: The only disadvantage of the heavy water is found to be its cost of production, but due to its effectiveness, It is preferred and used widely in India. It is also used in nuclear magnetic resonance.