Question

The oldest moon rocks are from the lunar Highlands and were formed when the early lunar crust was partially or entirely molten. These rocks of which only a few were returned by Apollo mission have nearly equal quantities of uranium-238 and lead-206. what is the age of these rocks?

Answer 1

lead - 206 is the last stage where Uranium - 238 decays to. Here Na no. of uranium-238 presente no. of Pb-206 present now, No= no. of wranium- 238 was there in the sample 7No (No. of U-238) + (10. P6-206) > N = N +N = 20 4-decay constant - e 7/2 = half life of U-238=4.468x18 yrs. Let t be the required time. from decay equation- - N= No erdt se sent ett T T T - at = 102 Ť in2 t = 112 a) to Tu-14.463 xro‘ystis (approx) age of those stocks are 4.468x10^yns 03 4.5 billion years (approx). the