Question

In Periodic Table,$4n + 2$ series is known as:
A) Actinium series
B) Thorium series
C) Uranium series
D) Neptunium series

Answer 1

To solve this we must know that $4n + 2$ series is a radioactive series. The radioactive series decay constantly. The decay chain is a series of radioactive decays of different radioactive decay products sequentially. This is also known as radioactive cascade.

Complete answer:
We know that the $4n + 2$ series is a radioactive series. The radioactive series decay constantly. The decay chain is a series of radioactive decays of different radioactive decay products sequentially. This is also known as radioactive cascade.
The actinium series is the $4n + 3$ chain of uranium-235. The actinium series is also known as actinium cascade. The series begins with the element actinium and thus, it is named as actinium series. The other elements of the actinium series are astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium and thorium.
Thus, option (A) is not correct.
The thorium series is the $4n$ chain of thorium-232. The actinium series is also known as thorium cascade. The series begins with the naturally occurring element thorium and thus, it is named as thorium series. The other elements of the thorium series are actinium, bismuth, lead, polonium, radium, radon and thallium.
Thus, option (B) is not correct.
The uranium series is the $4n + 2$ chain of uranium-238. The uranium series is also known as uranium cascade. The series begins with the naturally occurring element uranium and thus, it is named as uranium series. The other elements of the thorium series are astatine, bismuth, lead, polonium, protactinium, radium, thallium and thorium.
Thus, option (C) is correct.
The neptunium series is the $4n + 1$ chain of neptunium-237. The neptunium series is also known as neptunium cascade. The series begins with neptunium and thus, it is named as neptunium series. The other elements of the thorium series are bismuth and thallium.
Thus, option (D) is not correct.
Thus, $4n + 2$ series is known as uranium series.
Thus, the correct option is (C) is uranium series.

Note: The parent isotope undergoes decay and produces a daughter nuclei or daughter isotope. If the daughter isotope is unstable it further decays to form another daughter isotope. Example of radioactive decay is uranium having atomic number 92 decays to form thorium having atomic number 90.