Question

The amount of $NaOH$ in $750ml$ of $0.2M$ solution (Molecular weight $=40$) is:

• A. $2gm$
• B. $4gm$
• C. $6gm$
• D. $8gm$

Answer 1

The correct option is C $6gm$

Molarity (M): The number of moles of a solute dissolved in 1 L (1000 ml) of the solution is known as the molarity of the solution.

Molarity of a solution, $\left(M\right)=\frac{massofsolute}{molarmassofsolute}\times \frac{1000}{volumeofsolutioninmL}$
Given:
Molarity of $NaOH=0.2M$
Volume of $NaOH$ solution $=750mL$

Mass of NaOH $=\frac{40\times 0.2\times 750}{1000}=6g$

So, this solution contains 6gm of NaOH.