Question

What volume of rubbing alcohol is required to add in water to prepare $250$ mL of $70\%$ (v/v) solution?

• A. $125$ mL
• B. $150$ mL
• C. $175$ mL
• D. $200$ mL

Answer 1

The correct option is C $175$ mL

$\frac{\text{Vol. of alcohol needed}}{\text{Total vol. of solution}}\times 100=70\%$

$\Rightarrow \text{Vol. of alcohol needed}=250\text{mL}\times \frac{70}{100}=175\text{mL}$