Question Number 139108 by BHOOPENDRA last updated on 22/Apr/21
Answered by physicstutes last updated on 22/Apr/21
$$\lambda\:=\:\mathrm{0}.\mathrm{1317}\:\mathrm{year}^{−\mathrm{1}} ,\:{t}\:=\:\mathrm{21}.\mathrm{04}\:\mathrm{years},\:{N}_{\mathrm{0}} \:=\:\mathrm{1}\:\mathrm{g} \\ $$$$\mathrm{Using}\:\mathrm{the}\:\mathrm{decay}\:\mathrm{equation}: \\ $$$$\:{N}\:=\:{N}_{\mathrm{0}} {e}^{−\lambda{t}} \\ $$$$\:\:\:\:\:\:=\:\left(\mathrm{1}\right)\left({e}\right)^{\left(−\mathrm{0}.\mathrm{1317}\right)\left(\mathrm{21}.\mathrm{04}\right)} \mathrm{g}\:=\:\mathrm{0}.\mathrm{006}\:\mathrm{g} \\ $$