In a radioactive substance at t = 0, the number of atoms is 8×104. Its half life period is 3 years. The number of atoms 1×104 will remain after interval

(a) 9 years                (b) 8 years
(c) 6 years                (d) 24 years

(a) By formula N=N012t/T or 104=8×10412t/3
or 18=12t/3 or 123=12t/33=t3
Hence t = 9 years.

Difficulty Level:

  • 64%
  • 20%
  • 8%
  • 8%