Chapter 30, Problem 3STP

To determine

To Choose: The correct option.

Answer to Problem 3STP

Option $A$ is the correct answer.

Explanation of Solution

Introduction:

Alpha decay is a kind of radioactive decay in which the atomic nuclei that are unstable releases large amount of energy and at the same time removes the alpha particles.

The alpha particles which are released are called as helium nucleus. The total mass of alpha particles has large and also a positive charge.

When polonium $Po$ which has atomic mass number $210$ of and atomic number of $84$ undergoes alpha decay leads to the formation of lead with has atomic number $82$ .

The nuclear reaction is written as,

  $Po\to Pb+He$

In the above reaction, there are $126$ neutrons and $84$ protons in the nucleus of the Polonium. During the alpha decay, $\alpha$ particles are released which is the Helium that is released by the nucleus.

As the Helium has neutrons and protons the alpha decay process leads to decrease in the atomic number by $2$ and atomic mass number by $4$ and leads to the formation of lead $Po$ .

Conclusion:

Thus, option $A$ is the correct option.