Radioactivity was discovered by

A ) Kelvin

Explanation:

Radioactivity was discovered by Becquerel.
Radioactivity emerges from: Nuclear energy.
Radioactivity is measured by which device Geiger counter.
Thorium metal is not only magnetic but also radioactive Radioactive element are Plutonium, Thorium, Uranium.
Alpha rays is a positively charged particle emitted by a radioactive element.
A negatively charged particle emitted by a radioactive element during radioactive decay is called a Beta particle.
Radioactive isotopes are used in medicine for both diagnostic imaging and treatment.
A 100 g sample of a radioactive element has a half life of 5 days. 12.5grams of radioactive material will remain after 15 days.
Radioactive elements have atomic number greater than82.
Weak Nuclear Force is responsible for the radioactive decay of the nucleus.
The radioactive material must be placed in a box of Lead.
Radioactive cobalt 60 is used for curing: Cancerous cells.
Radioactive isotope present in atmosphere is: carbon -14.
Unstable nuclei are radioactive.When radioactivity rays are passed through air or any gas, they cause it to Ionize.