Half-Life Problems in Chemistry

What is the half-life of iodine-131?

• 32 days

• 16 days

• 8 days

• 4 days

After 32 days, how much iodine-131 remains from an initial 200 grams?

• 25 grams

• 50 grams

• 12.5 grams

• 6.25 grams

What is the rate constant K for iodine-131 if its half-life is 8 days?

• 0.04621

• 0.06931

• 0.13863

• 0.08664

How long does it take for 750 grams of sodium-24 to decay from an initial 800 grams?

• 45 hours

• 30 hours

• 15 hours

• 60 hours

What is the half-life of sodium-24?

• 15 hours

• 5 hours

• 10 hours

• 20 hours

What fraction of oxygen-15 remains after five half-lives?

• 1/32

• 1/4

• 1/16

• 1/8

How many minutes correspond to five half-lives of oxygen-15?

• 5 minutes

• 20 minutes

• 10 minutes

• 15 minutes

What is the initial percentage of a sample before any decay?

• 25%

• 50%

• 75%

• 100%

How many half-lives does it take for a 512g sample of element X to decay to 4g?

• 7

• 6

• 5

• 8

What is the half-life of element X if it takes 35 days to decay from 512g to 4g?

• 3 days

• 7 days

• 5 days

• 9 days