The normality of 5% (w/v) soln. of H3PO4 in the presence of phenolphtalein indicator is-----

5g H3PO4 is present in 100 ml of soln.

First calculate the moles of H3PO4 then calculate molarity.

i.e M  = n/V (ltrs.)

then Normality = Molarity x Valence factor

                         =  M X 5

APprove!