Question

Which of the following is the man-made radioactive disintegration series?
A. Thorium series
B. Neptunium series
C. Uranium series
D. Actinium series

Answer 1

When a nucleus of an unstable atom loses energy by emitting radiation such as alpha, beta and gamma rays it is known as radioactivity. Radioactivity is a natural process but can also be artificially induced.

Complete step by step solution:
The thorium series is a radioactive series that begins with thorium. Thorium is a naturally occurring element and is found in earth’s crust. Thorium is unstable and radioactive. Thus, all the elements in the thorium series are naturally occurring and radioactive.
Thus, thorium series is not a man-made radioactive disintegration series. Thus, option (A) is not correct.
The neptunium series is a radioactive series that begins with neptunium. Neptunium is not a naturally occurring element. Thus, neptunium is a man-made element. Thus, all the elements in the neptunium series are man-made and radioactive.
Thus, neptunium series is a man-made radioactive disintegration series. Thus, option (B) is correct.
The uranium series or the radium series is a radioactive series that begins with uranium. Uranium is a naturally occurring element and is found in earth’s crust. Uranium is unstable and radioactive. Thus, all the elements in the uranium series are naturally occurring and radioactive.
Thus, uranium series is not a man-made radioactive disintegration series. Thus, option (C) is not correct.
The actinium series is a radioactive series that begins with actinium. Actinium is a naturally occurring element and is found in earth’s crust. Actinium is unstable and radioactive. Thus, all the elements in the actinium series are naturally occurring and radioactive.
Thus, actinium series is not a man-made radioactive disintegration series. Thus, option (D) is not correct.
Thus, the man-made radioactive disintegration series is neptunium series.

**Thus, the correct option is (B) neptunium series.

Note: **
The emission of radiation from an unstable nucleus is known as natural radioactivity. Artificial radioactivity is the emission of radiation from naturally occurring isotopes bombarded with x-rays or gamma-rays.