Answer: Molar mass of acid is 40 g/mol

Explanation:-

Normality is defined as the umber of gram equivalents dissolved per liter of the solution.

Normality of NaOH= 0.5 N

Volume= 100 ml = 0.1 L

As we know 1 gram As we know 1 gram equivalents of acid will react with 1gram equivalent of base.

Thus 0.05 gram equivalents of  base will react with  0.05 gram equivalent of acid.

Molar mass=40g/mol