Sodium- 24 has a half-life of 15 hours. After 45 hours, how much sodium- 24 will remain of an original 50 point 0 - g sample?
Answer
A
6 point 2 5 g
B
25 point 0 g
C
5 point 5 6 g
D
16 point 7 g
Explanation
In 45 hours, three half-lives pass because 45 ÷ 15 = 3. The sample is halved three times: 50.0 g → 25.0 g → 12.5 g → 6.25 g. Therefore, 6.25 g remains, which is choice A.
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