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NEET2015PhysicsNuclear PhysicsActual

The half-life of radium is 1600 years. What is the fraction of sample undecayed after 6400 years?

Options

  1. A1 16
  2. B1 4
  3. C1 8
  4. D1 24

Correct answer

A. 1 16

Step-by-step solution

Half-life, T=1600 years Time of decay, t=6400 years Number of half-lives, n= t T = 6400 1600 =4 Fraction undecayed = N N₀ = ( 1 2 )^n= ( 1 2 )^4= 1 16

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