Sodium-24 has a half-life of 15 hours. How many half-lives will pass in 5 days?

• A. 12
• B. 8
• C. 4
• D. 6

Answer: (B)

Verified step by step guidance

1. Identify the half-life of Sodium-24, which is given as 15 hours.
2. Convert the total time period from days to hours to match the units of the half-life. Since 1 day = 24 hours, multiply 5 days by 24 hours/day to get the total time in hours.
3. Use the formula to find the number of half-lives passed: Number of half-lives = Total time elapsed / Half-life duration.
4. Substitute the values: Number of half-lives = (5 days × 24 hours/day) / 15 hours.
5. Simplify the expression to find how many half-lives occur in 5 days.