Q143. 87Ra221 is a radioactive substance having half-life of 4 days. Find the probability that a nucleus undergoes decay after two half-lives.Physics — NUST Mock 3 — Question 143 of 200A. 1B. 1/2C. 3/4D. 1/4Practice more Physics MCQs for entrance exam preparation on Examora.io.← Previous Question Next Question →