Question

The composition of an alpha particle can be expressed as
A. \[1{\rm{ }}P + 1{\rm{ }}N\]
B. \[1{\rm{ }}P + 2{\rm{ }}N\]
C. \[2{\rm{ }}P + 1{\rm{ }}N\]
D. \[2{\rm{ }}P + 2{\rm{ }}N\]

Answer 1

Hint: In the given question, we need to determine the composition of an alpha particle. For this, we have to use the configuration of doubly ionised helium atoms. Using this configuration, we will determine the number of protons and neutrons present in an alpha particle.

Complete step by step solution:
We know that an alpha particle is a doubly ionised helium atom.
So, its electronic configuration is \[{}_2H{e^4}\].
Here, \[He\] stands for helium atom.
Based on this configuration, we can say that there are two protons.
Also, the number of neutrons is given by
Neutrons \[ = 4 - 2 = 2\]
Thus, an alpha particle contains two protons and two neutrons.
Hence, the composition of an alpha particle can be expressed as \[2{\rm{ }}P + 2{\rm{ }}N\].

Therefore, the correct option is D.

Additional Information: When some radionuclides undergo an event known as alpha-decay, they release these particles from their nuclei. A doubly ionised helium atom, which has an atomic mass of four, is equivalent to the nucleus of an alpha particle. The first type of nuclear radiation to be recognised was alpha particles, often known as alpha radiation or alpha rays. Beta particles and gamma rays followed shortly after.

Note: Many students may make mistakes in writing the configuration of helium atoms. If so, then we can’t get the correct composition of an alpha particle. So, it is essential to write the configuration correctly to determine the number of protons and neutrons present in an alpha particle.