Question

Consider a radioactive nucleus A which decays to a stable nucleus C through the following sequence:

A→B→C

Here B is an intermediate nuclei which is also radioactive. Considering that there are N₀ atoms of A initially, plot the graph showing the variation of number of atoms of A and B versus time.

Answer 1

Consider radioactive nucleus A have N₀ atoms of A initially; or at t = 0, N_A = N₀ (maximum) whole N_B = 0. As time increases, N_A decreases exponentially and the number of atoms of B increases. After some time N_B becomes maximum. As B is an intermediate nuclei which is also radioactive, it also starts decaying and finally drops to zero exponentially by radioactive decay law. We can represent the situation as shown in the graph.