Question

You start out with 800 moles of a radioactive substance. After 24 hours, 100 moles remain. What is the half-life of the substance in hours?

Question 1 options:

12 hours


4 hours


8 hours


6 hours

Answer 1

The correct answer would be 8 hours

Step-by-step explanation:

Answer 2

The equation for the half life of a substance:

N(t) = N₀ (
`(1)/(2)`)
`^{\frac{t}{t_{(1)/(2) \ } }`

• N(t) = substance remaining
• N₀ = initial amount of substance
• t = time passed
• t
  `_{(1)/(2) }` = half life

Plug in the information you know into the equation:

100 = 800 (
`(1)/(2)`)
`^{\frac{24}{t_{(1)/(2) \ } }`

Now solve for
`t_{(1)/(2) }` and you will get 8 hours as the half life