SOLAR SYSTEM

Detailed explanation-1: -The initial number of atoms of a radioactive element with half life 100 days, is 9. 6×1026.

Detailed explanation-2: -Therefore, after one half-life, 50 percent of the initial parent nuclei remain; after two half-lives, 25 percent; and so forth. The intensity of radiation from a radioactive source is related to the half-life and to the original number of radioactive atoms present.

Detailed explanation-3: -Calculations Using the First Order Rate Equation: r = k[N] Since the rate of radioactive decay is first order we can say: r = k[N]1, where r is a measurement of the rate of decay, k is the first order rate constant for the isotope, and N is the amount of radioisotope at the moment when the rate is measured.

Detailed explanation-4: -Determine the original amount of the substance. Determine the amount of time for which the substance was measured. Determine the remaining amount of the substance after the time. Substitute these values into the half-life equation and solve for half-life.