If a radioactive element having half-life of 30 min is undergoing beta decay, the fraction of radioactive element remains undecayed after 90 min will be:
Options

Question

If a radioactive element having half-life of 30 min is undergoing beta decay, the fraction of radioactive element remains undecayed after 90 min will be:

G1 Physics · Accepted Answer

90 min corresponds to three half-lives. Fraction remaining = (1/2)³ = 1/8.