Question

Which characteristics are common to the three isotopes of hydrogen?

Answer 1

D should be the correct answer.  isotopes are atoms that have the same atomic number (number of protons) but different atomic masses (number of protons and neutrons).  isotopes also have the same number of electrons since atoms need to have equal numbers of protons and electrons to not be considered ions.  Since the number of protons determines the chemical properties of the atom, we can say that all isotopes have the same chemical properties due to the fact that all isotopes have the same atomic number.

I hope this helps.  Let me know in the comments if anything is unclear.