Question

Which element has three isotopes that are each known by a different name?

• A. Helium
• B. Oxygen
• C. Carbon
• D. Hydrogen

Hint:

Think of the special names protium, deuterium and tritium. Which element do they belong to?

Answer 1

The Correct Option is D

Go through each element and recall how its isotopes are usually named.

• Helium: isotopes are called helium-3 and helium-4, just the element name with a number.
• Oxygen: isotopes are oxygen-16, oxygen-17 and oxygen-18, again just numbered.
• Carbon: isotopes are carbon-12, carbon-13 and carbon-14, numbered the same way.
• Hydrogen: uniquely, its three isotopes get separate names, protium, deuterium and tritium, instead of just being numbered.

This special naming makes hydrogen the answer, so option D is correct.