Radioactive secular equilibrium occurs between a parent element A and its daughter element B. Under — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

At steady state, rate of decay of A = rate of decay of B, so $N_A \lambda_A = N_B \lambda_B$. Since $\lambda = 0.693 / T_{1/2}$, substituting yields $N_A / T_{1/2(A)} = N_B / T_{1/2(B)}$, which rearranges directly to $N_A / N_B = T_{1/2(A)} / T_{1/2(B)}$.