Q.Write two units of radioactivity. How are they interrelated?

Because $N = N_0 e^{-\lambda t}$ is exponential, taking $\log_{10}$ of both sides converts it into a straight line: $\log_{10}N = -\frac{\lambda}{2.303}t + \log_{10}N_0$. Since activity is directly proportional to N, the same straight-line rela …