Substance A has atomic mass number 16 and half life of 1 day. Another substance B has atomic mass number 32 and half life of 1 2 day. If both A and B simultaneously start undergo radio activity at the same time with initial mass 320 g each, how many total atoms of A and B combined would be left after 2 days

Step-by-step solution

Number of nuclei left after n half-lives is given by, N = N 0 1 2 t t 1 2 . As, N 0 A = 320 16 = 20   moles and N 0 B = 320 32 = 10   moles Then, N A = N 0 A 2 2 1 = 20 4 = 5 and N B = N 0 B 2 2 0 . 5 = 10 2 4 = 0 . 625 So total N   =   5 . 625 and number of atoms = 5 . 625 × 6 . 023 × 10 23 = 3 . 38 × 10 24