Question

To neutralize completely $20 \,mL$ of $0.1\, M$ aqueous solution of phosphorous acid $(H_3PO_3)$, the volume of $0.1\, M$ aqueous $KOH$ solution required is

• A. 10 mL
• B. 60 mL
• C. 40 mL
• D. 20 mL

Answer 1

Answer: (C)

40 mL

Answer 2

No. of gm equivalents of phosphorous acid = No. of gm equivalents of KOH $20?0.1?2$ ($n =$ factor) $= 0.1 ?V$ $= 0.1 ?V$ $V = \frac{4}{0.1} = 40ml$