The radioactivity of a sample is at a time and at a time . If the half-life of the specimen is , the — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Activity $R = \lambda N$. Initial nuclei $N_1 = R_1/\lambda$, final nuclei $N_2 = R_2/\lambda$. Atoms disintegrated = $N_1 - N_2 = \frac{R_1 - R_2}{\lambda}$. Substituting $\lambda = \frac{0.693}{T}$, we get disintegrated atoms = $\frac{(R_1 - R_2)T}{0.693}$. Therefore, correct answer is D.