Question

Molarity of pure $D_{2}O$ will be (assume density of $D_{2}O$ is $1gm{L}^{-1}$)

• A. $55.56M$
• B. $18M$
• C. $20M$
• D. $50M$

Answer 1

The correct option is D $50M$

Molarity $=\frac{\text{No. of moles}}{Volumeofsolution}$
Let, volume of the solution be $1litre$
Given, density of $D_{2}O$ is $1gm{L}^{-1}$
So, $1$ litre of solution contains $1000g$ solution.
$\therefore$
$No.ofmoles=\frac{\text{Total mass}}{\text{Molar mass}}=\frac{1000}{20}=50mol$
$Molarity=\frac{50mol}{1litre}=50M$