radioactive radium has a half-life of approximately 1620 years. what percent of a given amount remains after 100 years?
95.8%;radio active radium disintegrates by first order kinetics; let ‘x’ be the radium left at time 't’
and X be initial amount.so dx/dt=a.x;solving we get x=Xe^(-at) (a is constant);
put x=X/2 and t=half life period;
we get the value of constant “a”;
so % of radium left at time “t” is x/X*100=exp^(-at)*100;