Which isotope of hydrogen with a half-life of 12.32 years has a nucleus that contains one proton and two neutrons?
Isotopes of hydrogen one tritium nucleus captures two neutrons from the other, becoming a nucleus with one proton and four neutrons. The remaining proton may be detected, and the existence of hydrogen-5 deduced. It decays through double neutron emission into hydrogen-3 (tritium) and has a half-life of at least 910 yoctoseconds (9.1 × 10 seconds). H decays either through triple neutron emission into hydrogen-3 (tritium) or quadruple neutron emission into hydrogen-2 (deuterium) and has a half-life of 290 yoctoseconds (2.9 × 10 seconds). H consists of a proton and six neutrons. It was first synthesised in 2003 by a group of Russian, Japanese
Isotopes of hydrogen observed to decay, and hydrogen-1 is therefore considered a stable isotope. Some grand unified theories proposed in the 1970s predict that proton decay can occur with a half-life between 10 and 10 years. If this prediction is found to be true, then hydrogen-1 (and indeed all nuclei now believed to be stable) are only observationally stable. To date, however, experiments have shown that the minimum proton half-life is in excess of 10 years. H (atomic mass u), the other stable hydrogen isotope, is known as "deuterium" and contains one proton and one neutron in its nucleus. The nucleus of deuterium