Meq of oxalic acid =Meq of KMnO4
V*0.1=250*8/100*3L6*1000=6.3 litres How mass is equivalent is this a formula??

Dear student,

Equivalent mass is the mass of one equivalent of any substance.
Mathematically, it is calculated as follows.

$$\begin{gathered} Equivalent mass = \frac{Molecular mass}{Number of electrons gained or lost \left(n\right)} \\ Normality \left(N\right) = \frac{Gram equivalent weight of solute}{Volume of solution \left(liter\right)} = \frac{Weight}{Equivalent weight} \\ {N}_1{V}_1 = N_2{V}_2 \\ 0.1 \times V = \frac{250 \times 8}{100 \times 31.6} \times 1000 \\ V = 6.3 liter \end{gathered}$$

This question if from the concept of titration and in titration molar equivalent mass is equal in the equivalence point.

Hence, the correct option is (a).

Regards