Question

based on the mass of lactose that you isolate from 1 mL of skim milk, calculate the percent composition of lactose in skim milk.

mass of lactose= 0.28 grams

Answer 1

Do you want mass percent or mass/volume percent? I will assume you want mass/volume percent.
% w/v = [(mass lactose)/mL]*100 = ?

Answer 2

0.28/1*100= idek how to do it

Answer 3

(0.28/1)*100 = 28/1 = ?