A level PhysicsWatch
Caesium 137 has a half life of 28 years. first they ask for the decay constant and then the activity of a sample of mass 0.05g. I get the decay constant as 7.84x10^-10 per second and the activity to be 1.72x10^11 Bq
And, please specify at which time u want to find the activity. U should use the formula A=Ao e^(-lambda x t).
Lamda is decay constant and Ao is initial activity of the sample.