To neutralise completely 20 mL of 0.1 M aqueous solution of phosphrous acid `(H_(3)PO_(3))`, the volume of 0.1 M aqueous KOH solution required is :

Monjur Alahi

To neutralise completely 20 mL of 0.1 M aqueous solution of phosphrous acid `(H_(3)PO_(3))`, the volume of 0.1 M aqueous KOH solution required is :
A. 40 mL
B. 20 mL
C. 10 mL
D. 60 mL


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Correct Answer - a
Since `H_(3)PO_(3)` is dibasic, 0.1 M solution =- 0.2 N solution.
`underset(("Acid"))(N_(1)V_(1))=underset(("Base"))(N_(2)V_(2))`
`(0.2 N)xx20 mL)=(0.1N)xxV_(2)`
`V_(2)=((0.2N)xx(20mL))/((0.1N))=40 mL.`

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