`0.63 g` of diabasic acid was dissolved in water. The volume of the solution was made `100 mL`. `20 mL` of this acid solution required `10 mL` of `N//5 NaOH` solution. The molecular mass of acid is:

Options

A. 3
B. 6
C. 12
D. 24

Answer

C

Explanation

`V_(a)N_(a) = V_(b)N_(b), 40 xx N_(a) = 28 xx (1)/(10) rArr N_(a) = 0.07`
eqts. of metal =eqts. of acid reacted
m. eqts of acid reacted with metal `= 100 - 70 = 30`
`(0.36)/(E) = (30)/(1000) :. E w` of metal = 12