The heaviest naturally occurring element is

a. uranium

c. xenon

b. iron

d. silver

The best answer is a - uranium.

The heaviest naturally occurring element is Uranium. It has a density of 18.95g/cubic cm. Its most common isotope is uranium 238, which has nucleus that has 92 protons and 146 neutrons.

On earth, it is 40 times more abundant than silver and almost as common as tin. Its half life is 4.47 billion years.

Uranium was discovered by a person known as Martin Klaproth of Germany in the year 1789. He named it after the planet Uranus.