The exact volume of 1M NaOH  solution required to neutralize 50 mL 1M H3PO3solution and 100 ml 2M H3PO2 respectively are

Mb=1M Ma=1M H3  PO3 +2NaOH→Na2 HPO3 +2 H2 OVb=xVa=50mLnb=2na=1    MaVana=MbVbnb1×501=1×x2x=100ml    NaOH+H3PO2→NaH2PO2+H2O    Mb=1M    Ma=2M    μaVana=μbVbnb2×1001=1×x1Vb=x    Va=100    nb=1    na=1    x=Vb    =200mL      or use V1N1=V2N2