Answer:2 half life
Step-by-step explanation:
Radioactive decay is the process in which the nuclei of radioactive atoms emit charged particles and energy. This is due to the presence of unstable nuclei in Radioactive isotopes and when the nuclei emit radiation, they become more stable.
Half life is the amount of time it takes half the amount of isotopes to decay.when one half life reaches,50% of the isotope decays, leaving behind 50% of it.
In another half life,half of the 50% which is 25% decays.
Therefore in two half life,75% of the isotope decays,which is three quaters of it