Question

$3.011\times {10}^{22}$ formula units of $NaOH$ were added in water to make a solution of 250 mL. The strength of solution in g/L is:

• A. 8 g/L
• B. 16 g /L
• C. 4 g/L
• D. 2 g/L

Answer 1

The correct option is A 8 g/L

$\text{Moles of}NaOH=\frac{3.011\times {10}^{22}}{6.022\times {10}^{23}}=0.05$

$\text{Mass of}NaOH=0.05\text{mol}\times 40\text{g/mol = 2 g}$

Strength of the solution in g/L $=\frac{\text{mass of solute}}{\text{total volume of solution (mL)}}\times 1000$
$=\frac{2}{250}\times 1000=8g/L$