Adioxin-contaminated water source contains 0.085% dioxin by mass. how much dioxin is present in 2.5 l of this water?

 The mass of dioxin  present in  2.5L of  water  is  2.125 grams

                calculation
convert  the 2.5 l to Ml  =  2.5 x1000 = 2500 Ml

density  of  water  is =  1g/ml

mass  is  of  water is therefore =  density  x volume

= 2500 Ml  x 1g/ml = 2500 grams
by of the below  formula of  calculating  of % mass

that is  mass of the solute / mass  of   the solution  =  % mass 

let  the mass of  solute  be represented by y
mass  of solution = 2500 g
%  mass = 0.085% =  0.085/100  into  fraction

  by  subsituting  in the  formula 

  =y/2500= 0.085/100
  cross  multiplication

100y =212.5

divide both side   by 100

y=  2.125 grams