Tritium is radioactive and decays by emitting a beta particle. Let us work out what it decays into:
Secondly, the charge after must be the same as before. We have 1 proton on the left (1+ charge) and, so far, 1 electron on the right (1 charge). So: +1 = (charge of X) + (1) The charge of X must be +2, giving:
