Question 48
Radioactivity and Nuclear PhysicsA radioactive substance has a half-life of 80 days. If the initial number of atoms in the sample is 6.00 × 1010, how many atoms would remain at the end of 320 days?
- A.3.75 × 109
- B.7.50 × 109
- C.3.00 × 1010
- D.5.63 × 1010
Show the answer and explanation
Answer: A (3.75 × 109)
Explanation
320 days is 4 half-lives, so (½)4 = 1/16 remains: 6.00 × 1010 ÷ 16 = 3.75 × 109.