Question

is not an isotope of hydrogen.

• A. Protium
• B. Deuterium
• C. Tritium
• D. Hydronium

Answer 1

The correct option is D Hydronium

Protium, deuterium and tritium are isotopes of hydrogen. However, hydronium is not. Hydronium $\left(H_3{O}^{+}\right)$ is a cation formed when $H^{+}$ ions combine with water.

$H^{+}+H_{2}O\underset{}{\overset{}{\to }}{H}_3{O}^{+}$