Answer : If a reactant undergoes first order kinetics and the initial reactant was R is consumed in 4 half lives then,
the first half life would undergo from 1 to 1/2R;
the second half life will go from 1/2R to 1/4R;
in third half life it will undergo from 1/4R to 1/8R;
And finally in fourth half life it will go from 1/8R to 1/16R.
So, it means [tex]15/16^{th} [/tex] is utilized and only 1/16 R remains
