The volume of 0.1N dibasic acid sufficient to neutralize 1g of a base that furnishes 0.04 mole of OH⁻ in aqueous solution is:

Apply the Law of equivalence we get,
equivalence of acid = equivalence of base
0.1 × V = 0.04 × 1
V = 0.4 L = 0.4 × 1000 = 400 ml
Hence, the correct option is 400 ml