The mineral monazite is a rich source of thorium, available in large quantity in kerala. A typical monazite sample contains 9% ThO_(2) and 0.35% U_(3)O_(8). .^(208)Pb and .^(206)Pb are the stable end products in the radioactive decay series of .^(232)Th and .^(238)U respectively. All the lead in monazite is of radiogenic origin. The isotopic ratio of .^(208)Pb//^(232) Th. was found to be 0.104. The half lives of Th and U are 1.41 xx 10^(10) years adn 4.47 xx 10^(9) years respectively. Estimated isotopic ratio of .^(206)Pb//^(238) U in the monazite sample will be:

The mineral monazite is a rich source of thorium, available in large q

1.	The mineral monazite is a rich source of thorium, available in large quantity in kerala. A typical monazite sample contains 9% ThO_(2) and 0.35% U_(3)O_(8). .^(208)Pb and .^(206)Pb are the stable end products in the radioactive decay series of .^(232)Th and .^(238)U respectively. All the lead in monazite is of radiogenic origin. The isotopic ratio of .^(208)Pb//^(232) Th. was found to be 0.104. The half lives of Th and U are 1.41 xx 10^(10) years adn 4.47 xx 10^(9) years respectively. Estimated isotopic ratio of .^(206)Pb//^(238) U in the monazite sample will be:
Answer» 0.166 0.266 0.366 0.466 Answer :C