Question

Which element is considered radioactive among the options given below?

• A. Sodium
• B. Gold
• C. Thorium
• D. Neon

Answer 1

Answer: (C)

Thorium

an element subject to spontaneous degeneration of its nucleus accompanied by the emission of alpha particles, beta particles, or gamma rays. All elements with atomic numbers greater than $83$ are radioactive. Naturally occurring radioactive elements include radium, thorium, and uranium. Several radioactive elements not found in nature have been produced by the bombardment of stable elements with subatomic particles in a cyclotron.