Question

step by step please! need help understanding

6. Terbium-152 is a positron emitter with a half-life of 18.0 hours. How long would take for the activity in a sample of this nuclide to decay to exactly three-eighths of its original value? a. 32.8 hours b. 28.8 hours c. 23.6 hours ! d. 25.5 hours e. 48.9 hours 7. The specific activity of a carbon sample from the bones of a mummy in a secret como recently discovered in Egypt is found to be at a level which is 60.0% of that of living plants. Calculate the age of the artifact. ("C:ty = 5730 years) a. 3438 years b. 2865 years ! c. 4223 years d. 2111 years e. 8444 years

Answer 1

In (SA) = kt a time t At initial concentration At concentration after k is rate constant K = 0.693 It is the half-life. InCA - INCA = kt Inca = - kt + InCA If we plot a graph (us) t we get a with a slope of Sk' intercept InCA of Inca straight line and

wloo 0.693 18hr | (+) x 18 km 0.693 t= 25.426 hours = 25.5 hours. - A = 0.6CA.. CAO T. 0.693 0.6CA 5730 years rs tx In low) x 5730 years 0.693 t= 4223 years