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A 60.0-g sample of fermium-253 was placed in a sealed vessel 9.0 days ago. Only 7.5 g of this isotope is now left. What is th
half-life of fermium-253?
3.0 days
4.5 days
17.5 days
20.0 days

Respuesta :

Answer:

A

Explanation:

3 days later: 60/2=30

6 days later: 30/2=15

9 days later: 15/2=7.5

Eduard22sly

The half-life of the fermium-253 placed in the sealed vessel is 3 days

How to determine the number of half-lives

  • Original amount (N₀) = 60 g
  • Amount remaining (N) = 7.5 g
  • Number of half-lives (n) =?

2ⁿ = N₀ / N

2ⁿ = 60 / 7.5

2ⁿ = 8

2ⁿ = 2³

n = 3

How to determine the half-life

  • Number of half-lives (n) = 3
  • Time (t) = 9 days
  • Half-life (t½) =?

t½ = t / n

t½ = 9 / 3

t½ = 3 days

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