Understanding Radioisotope Decay and Half-Life

What is the concept of half-life used to describe?

• The time it takes for half of a radioisotope to decay.

• The time it takes for a radioisotope to double in mass.

• The time it takes for a radioisotope to completely decay.

• The time it takes for a radioisotope to become stable.

If a 100-gram sample undergoes one half-life, how much of the original sample remains?

• 100 grams

• 50 grams

• 25 grams

• 75 grams

Which isotope has a half-life of 4.51 billion years?

• Carbon-14

• Calcium-37

• Uranium-238

• Potassium-40

How many half-lives have passed if 1/8 of the original sample remains?

• 1 half-life

• 2 half-lives

• 3 half-lives

• 4 half-lives

What is the half-life of an element if 32 days have passed and 4 half-lives have occurred?

• 10 days

• 4 days

• 6 days

• 8 days

If 1/8 of a Krypton-74 sample remains after 34.5 minutes, what is its half-life?

• 11.5 minutes

• 34.5 minutes

• 23 minutes

• 17.25 minutes

How many days are required for 200 grams of radon-222 to decay to 50 grams?

• 3.8 days

• 7.6 days

• 11.4 days

• 15.2 days

What is the remaining mass of a 10-gram sample of potassium-40 after one half-life?

• 2.5 grams

• 5 grams

• 10 grams

• 7.5 grams

If a sample undergoes 3 half-lives, what fraction of the original sample remains?

• 1/2

• 1/4

• 1/8

• 1/16

What is the half-life of potassium-40?

• 36.08 hours

• 48.44 hours

• 24.72 hours

• 12.36 hours