Question

Which element is used in atomic reactors to control the speed of neutrons?

• A. $B$ & $Cd$
• B. $B$ & $Fe$
• C. $Cd$ & $Al$
• D. $Na$ & $K$

Answer 1

The correct option is A

$\mathrm{B}$ & $\mathrm{Cd}$

Controlled reactions: During nuclear fission reactions, the speed of neutrons are required to control to prevent further reaction.

Prevention of nuclear fission reactions:

For this purpose, the controlling rods are used in these reactions. The neutrons are absorbed on the surface of these rods without their own fission and prevent them to react further. These rods are made up of boron ($\mathrm{B}$), Silver ($\mathrm{Ag}$), Indium ($\mathrm{In}$) and cadmium ($\mathrm{Cd}$)

Final answer:

Hence, the option (A) is correct.