a) Potassium-40 undergoes three different modes of radioactive decay (Beta decay, Positron decay, and Electron Capture decay). Write balanced nuclear reactions for each of these decay modes. Are the products stable (not radioactive)?

b) Potassium-40 has a natural abundance of 0.0118%. How many atoms of potassium-40 are present in a 1.35 g sample of KCl?