Which radioactive isotope is used to determine the activity of thyroid gland?

Give one example of a radioactive isotope which is used as a fuel in the reactors of nuclear power plants.

Name the radioactive isotope which is used in the treatment of cancer.

State one use of radioactive isotopes in industry.

State whether the following statement is true or false:

Radioactive isotope of iodine is used for making the medicine called tincture iodine.