After 500 years, a sample of Radium-226 has decayed to 80.4% of its original mass. Find the half-life of Radium-226 What is the activity of 1gram of radium-226?The activity is given as the product λN, where λ is the decay constant and N is the number of nuclei that decay. Given that are sample is radium-226, with a half-life of 1600 years