NEET Physics Nuclei Questions Solved


Two radioactive materials X1 and X2 have decay constants 10λ and λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X1 to that of X2 will be 1/e after a time

(a) 1/(10λ)                   (b) 1/(11λ)
(c) 11/(10λ)                 (d) 1/(9λ)

(d) N1=N0e-10λt and N2=N0e-λt

N1N2=1e=e-1=e-10λ+λt=e-9λtt=19λ

Difficulty Level:

  • 10%
  • 34%
  • 15%
  • 43%
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