Question

$0.16g$ a dibasic acid required $25mL$ of decinormal $NaOH$ solution for complete neutralisation. The molecular mass of the acid is:

• A. $32$
• B. $64$
• C. $128$
• D. $256$

Answer 1

Answer: (C)

$128$

$Normality=\frac{mass\left(given\right)}{eq.mass}\times vol.\left(inlitre\right)0.1=\frac{0.16}{eq.mass}\times \frac{1000}{25}\Rightarrow eq.mass=\frac{0.16\times 40}{0.1}eq.mass=64\Rightarrow mol.mass=2\times eq.mass=2\times 64=128\left(2fordibasicacid\right)$