The number of oxalic acid molecules in 100 ml of 0.02 N oxalic acid is

Normality=Molarity × Valence factor∴  Molarity =NormalityValence factorValence factor  for  oxalic  acid=mol.  wt.  of  oxalic  acidEq.  wt.  of  oxalic  acid=mol.  wt.  of  oxalic  acidmol.  wt.  of  oxalic  acid×2=2As  basicity  of  oxalic  acid  is 2 & E=Mol.wt.2Molarity=202 = 0.01Number  of  millimoles=0.01 × 100Number  of moles  =  0.001∴   Number  of  oxalic  acid  molecules=0.001 ×  6.023 × 1023                                                    =  6.023 × 1020