Question

The radioactive isotope of radium has a half-life of 1600years. The mass of a 100g sample of radium will be —g after 200years

Answer 1

N(t) = N₀ e$^{(\frac{-0.693t}{t^{1/2}})}$

t = 200

N₀ = 100

t^1/2 = 1600

N(200) = 100×e$^{(\frac{-0.693×200}{1600})}$

N(200) = 100×e$^{(\frac{-138.6}{1600})}$

N(200) = 100×e^(-0086625)

N(200) = 91.7 gram

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