For a radioactive nuclide with a decay constant , which of the following expressions correctly repre — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Options A, B, and C are true and derived directly from the first-order decay equation $N_t = N_0 e^{-\lambda t}$. The remaining fraction is $N_t/N_0 = e^{-\lambda t}$, while the decayed fraction is $(N_0 - N_t)/N_0 = 1 - e^{-\lambda t}$. Activity follows the same exponential drop. Option D is incorrect; the correct formula for mass remaining after $n$ half-lives is $N_0(1/2)^n$.