The weight of oxalic acid that will be required to prepare a $1000 \mathrm{mL} (\mathrm{N}/20)$ solution is:

Mo!. wt. of oxalic add, ${\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\cdot 2{\mathrm{H}}_2\mathrm{O}=(2\times 1)+(2\times 12)+(4\times 16)+2\left\{\right(2\times 1)+16]=126\mathrm{g}1{\mathrm{mol}}^{-};$

Eq. wt. of oxalic acid $=$ Mol. wt./charge on cation $=\frac{126}{2}=63.$

But  Normality $=\frac{wt}{\text{ Eq.wt. }}\times \frac{1000}{\text{ vol in inL }}\frac{1}{20}=\frac{71}{63}\times \frac{1000}{1000}; \mathrm{w}=\frac{63}{20}.$