NEET Physics Nuclei Questions Solved


The half life of the isotope Na1124 is 15 hrs. How much time does it take for 78th of a sample of this isotope to decay

(a) 75 hrs               (b) 65 hrs
(c) 55 hrs               (d) 45 hrs

(d) Undecayed isotope =1-78=18

NN0=12t/T18=12t/15t15=3

or t = 45 hours

Difficulty Level:

  • 16%
  • 22%
  • 16%
  • 48%
Crack NEET with Online Course - Free Trial (Offer Valid Till August 24, 2019)