Question

The radioactive isotope used in the treatment of cancer has to be a good source of radiations.
 (A) $\beta $
 (B) $\alpha $
 (C) $\gamma $
 (D) IR

Answer 1

Hint
We know that X-rays, gamma rays and beta particles are all used in medicine to treat internal organs. We will therefore choose our answer in accordance to the question given and the knowledge about radioactivity we possess.

Complete step by step answer
$\gamma $ rays are produced when the nuclei of a radioactive atom reach an excited state, by emission of $\alpha $ and $\beta $ particles. Gamma rays are used to kill cancer cells, to sterilize medical equipment and in radioactive tracers. Therapy in which $\gamma $ -rays are used is named as radiation therapy.
Correct option is (C).

Note
To attempt this question one must have ample knowledge about radioactive substances and radiations. Not in this question, but sometimes X-Ray might be an option and students often choose that because of its popularity in the medical field.