Answer to Question #175972 in Physics for Gian

Question

Sodium-24 has a half-life of 15 hours. How much sodium-24 will remain in an 18.0g sample after 69 hours

Answer 1

$$m=m_0\cdot 2^{-\frac{t}{T}}\\m=18\cdot 2^{-\frac{69}{15}}=0.742\ g$$