Question

What is the sum of protons, electrons and neutrons in the heaviest isotope of hydrogen?

Answer 1

The heaviest isotope of hydrogen is tritium$31H$. This has 1 proton and 1 electron as this is an isotope of hydrogen. Remember, isotopes just have a different number of neutrons, the number of electrons and protons remain the same. The number of neutrons is 2 here. So, the answer would be 4.