Half-life of thorium is `1.5xx10^10` y. How much time is needed for 20% of thorium to disintegrate ?

The half-life of a first-order reaction is 1.5 hours. How much time is needed for 94% of the reactant to change to product?

The half life of radium is 1600 years . In how much time will its (15)/( 16) fraction disintegrate ?

The half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its (1)/(16) th parts ?

Calculate the half-life of uranium if its initial mass of 1 g is reduced by 2 mg in 5 years by disintegration into thorium and an alpha -particle.

The half-life period of U^(234) is 2.5 xx 10^(5) years. In how much is the quantity of the isotope reduce to 25% of the original amount?

The half-life period of U^(234) is 2.5 xx 10^(5) years. In how much is the quantity of the isotope reduce to 25% of the original amount?