Question

If by mistake some radioactive substance gets inside the human body, then from the point of view of radiation damage, the most harmful will be one that emits
(A) $\gamma $-rays
(B) Neutrons
(C) $\beta $-particle
(D) $\alpha $-particle

Answer 1

Hint: A radioactive element can decay in three ways: alpha decay, beta decay, and gamma decay. The nuclear disintegration process that generates alpha particles is known as "alpha decay." The term "beta particle" refers to the energetic electron that is liberated from the nucleus during the disintegration of $\beta $-ray. After radioactive decay, the nucleus of some radionuclides emits a packet of electromagnetic energy (photons) known as a gamma ray.

Complete step by step solution:
If by mistake some radioactive substance gets inside the human body, then from the point of view of radiation damage, the most harmful will be one that emits $\gamma $-rays. The main reason for its harmful nature is its high penetrating power.

The human body can be completely penetrated by gamma rays, which can then generate ionizations that harm DNA and tissue. Gamma rays have a very high energy that enables them to penetrate almost everything. Even bones and teeth are not a limit to them. This makes gamma rays extremely hazardous. They are capable of mutating genes, destroying living cells, and causing cancer.
Correct Option: (A) $\gamma $-rays.

Additional Information: Alpha, beta, and gamma rays are three distinct forms of radiation that radioactive substances release, according to British physicist Ernest Rutherford. Among the three different types of rays, alpha particles are the heaviest particles. At close range, a large number of atoms can be ionised by alpha radiation. It's because wearing rubber gloves is a necessity before handling radioactive items that release alpha particles.

Note: The gamma rays have more energy as compared to the alpha and beta particles. As these rays can penetrate most of the substances, therefore, it is also known as “penetrating” radiation.