Ans. 3.0 % (w/v) means 3.0 gram of the drug in 100 mL of the
solution.
Now,
100.0 mL of the solution has 3.0 gram of drug
       Or, 1.0
mLÂ Â Â Â Â Â Â Â Â Â Â Â Â
-Â Â Â Â Â Â Â Â Â Â
-Â Â Â Â (3.0 g / 100.0 mL) of drug
       Or, 2.0 mL
          Â
-Â Â Â Â Â Â Â Â Â Â
-Â Â Â Â (3.0 g / 100.0 mL) x 2.0 mL of
drug  Â
                                              Â
= 0.06 gram of drug
                                              Â
= 6
mg                       Â
[1 g = 100 mg]
Thus, 2.0 mL of the given solution has 6.0 mg drug.
