An ore of uranium is found to contain and in the mass ratio of 1:0.1. The half-life period of is yea — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Mass ratio U:Pb = 10:1. Mole ratio $N_{Pb}/N_U = (1/206) / (10/238) = 238/2060 = 0.1155$. Initial uranium $N_0 = N_U + N_{Pb}$. $N_0/N_U = 1 + 0.1155 = 1.1155$. Age $t = \frac{2.303}{\lambda} \log(1.1155) = \frac{4.5 \times 10^9}{0.3} \times 0.048 = 7.2 \times 10^8 \text{ years}$. Therefore, correct answer is A.