# For a radioactive material , half-life is 10 minutes . If initially there are 600 number of nuclei…

Q: For a radioactive material , half-life is 10 minutes . If initially there are 600 number of nuclei , the time taken (in minutes) for the disintegration of 450 nuclei is

(a) 30

(b) 15

(c) 10

(d) 20

Ans: (d)

Sol: N = 600 – 450 = 150

N/N0 = (1/2)n

150/600 = (1/2)n

1/4 = (1/2)n

n = 2

Number of half life = 2

t = n T1/2

t = 2 × 10