Question

$12.5mL$ of a solution containing $6g$ of a dibasic acid in $1L$ was found to be neutralized by $10mL$ of a decinormal solution of $NaOH$. The molecular mass of the acid is:

• A. $110$
• B. $75$
• C. $120$
• D. $150$

Answer 1

The correct option is D $150$

$N_1{V}_1\left(acid\right)=N_2{V}_2\left(base\right)$
$N_1\times 12.5=\frac{1}{10}\times 10$
$N_1=\frac{1}{12.5}$
$Strength=N\times Ew$
$6=\frac{1}{12.5}\times Ew$
$Ev=75$
Molar mass $=Equivalentmass\times Basicity$
$=75\times 2=150$.