NEET Physics Nuclei Questions Solved


A radioactive material decays by simultaneous emission of two particles with respective half lives 1620 and 810 years. The time (in years) after which one- fourth of the material remains is 
(a) 1080         (b) 2430
(c) 3240         (d) 4860

(a) λ=λ1+λ21T=1T1+1T2

 T=T1T2T1+T2=810×1620810+1620=540 years

Hence 14th of material remain after 1080 years.

Difficulty Level:

  • 48%
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  • 16%
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