<p>0.3g of an oxalate salt was dissolved in 100 mL solution. The solution required 90 mL of N/20&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>K</mi><mi>M</mi><mi>n</mi><msub><mi>O</mi><mn>4</mn></msub></math>&nbsp;for complete oxidation. The % of oxalate ion in salt is:</p>