Question

$1.25$ g of a solid dibasic acid is completely neutralised by $25$ mL of $0.25$ molar $Ba(OH{)}_2$, solution. Molecular mass of the acid is

• A. $100$
• B. $150$
• C. $120$
• D. $200$

Answer 1

The correct option is D $200$

As we know that,
$M=\frac{W\left(gm\right)\times 1000}{V\left(mL\right)\times m\left(gm\right)}$
whereas,
W= wt. of solute =1.25g
V= Volume of solvent =25mL
M= Molarity of solvent =0.25M
m= mol. wt. of solute =?

∴$0.25=\frac{1.25\times 1000}{25\times m}$

⇒m=200gm

Hence the molecular mass of acid is 200 gm.

Option D