Question

preparation of m/20 pxalic acid solution

Answer 1

Molecular formula of  oxalic acid: H2C2O4. 2H2O.
Molecular Wt. = 126. but here n/2 so = 63
to prepare 500 ml m/20 solution of acid 63 ×500 = 1.57 g of oxalic acid required.
                                                         (20×1000)
 dissolved 1.57g acid in water and make it 500ml

Answer 2

Molecular formula of solid crystalline oxalic acid: H2C2O4, 2H2O.
 Its Molecular Wt. 126.
 Hence, to prepare 250 ml M/20 oxalic acid solution 126*250/(20*1000) = 1.575 gram of oxalic acid is to be dissolved in water in a 250 ml volumetric flask.