`10 mL` of `0.2 N HCl` and `30 mL` of `0.1 N HCl` to gether exaclty neutralises `40 mL` of solution of `NaOH`, which is also exactly neutralised by a solution in water of `0.61 g` of an organic acid. What is the equivalent weight of the organic acid?

Options

A. 61
B. 91.5
C. 122
D. 183

Answer

C

Explanation

`10 mL` of `0.2 N HCl + 30 mL` of `0.1 N HCl -= 40 mL` of `NaOH (-= 0.61 g` organic acid)
mEq of `HCl -= mEq` of `NaOH -= mEq` of orgainc acid
`10 xx 0.2 + 30 xx 0.1 -= (0.61)/(e) xx 100`
`5 = (0.61 xx 1000)/(E)`
`E = (610)/(5) = 122`