NEET Physics Nuclei Questions Solved


A radioactive substance has a half life of 60 minutes. After 3 hours, the fraction of atom that have decayed would be

(a) 12.5%               (b) 87.5%
(c) 8.5%                 (d) 25.1%

(b) N=N012tT1/2 Hence fraction of atoms decayed
= 1-NN0=1-12tT1/2=1-123×6060=78
In percentage it is 78×100=87.5%

Difficulty Level:

  • 38%
  • 50%
  • 5%
  • 9%
Crack NEET with Online Course - Free Trial (Offer Valid Till August 26, 2019)