The number of neutrons in the most common isotope of hydrogen is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 0
The most common isotope of hydrogen is protium (\(^{1}_{1}\mathrm{H}\)), which makes up more than 99.98% of natural hydrogen. Its nucleus is a single proton with no neutron: the mass number 1 equals the atomic number 1, so the number of neutrons is \(1-1=0\). The other two isotopes are deuterium (1 neutron) and tritium (2 neutrons).