Question

Which radioactive isotopes are used to detect tumours?
(A) $^{74}As$
(B) $^{24}Na$
(C) $^{131}I$
(D) $^{60}Co$

Answer 1

Hint: Revise the concept of radioactivity. Think about the medical applications of radioactive isotopes. Think about the technique which is used to detect tumours and cancer. Take a look at the options and then accordingly, choose the correct answer.

Complete step by step solution:
- Radioactivity is the property of radioactive atoms to emit radiation spontaneously. It is better known as radioactive decay.
- In radioactive decay, an unstable nucleus of a radioactive atom emits energy spontaneously.
- Radioactivity is widely used in the medical field for diagnosis and treatment of various diseases.
- Radiation is used to get the diagnostic information about the functioning of various organs in the human body.
- Radiotherapy is the radiation therapy used in treatment of cancer by weakening the cancer cells using radiation.
- Arsenic-74 and Technetium-99 are used to detect tumours.
- Sodium-24 is used for finding out electrolytic balance in the body.
- Iodine-131 is widely used in treating thyroid cancer and in diagnostics of thyroid functions.
- Cobalt-60 is used for gamma ray irradiation of cancer for arresting cancer cells.
- Therefore, the isotope used for detection of tumours is $^{74}As$.

- Therefore, the answer is option (A).

Note: Remember radioactive decay is the process in which an unstable nucleus of an atom will emit radiation spontaneously. Radioactive isotopes are widely used in medical diagnostics called imaging like X-ray, PET, mammography, CT-scan, etc. All these techniques of diagnostics come under the umbrella of radiology.