Question

How many grams of $NaOH$ are needed to make $100g$ of a $5$% solution?

• A. $2$
• B. $5$
• C. $20$
• D. $40$
• E. $95$

Answer 1

Answer: (B)

$5$

Let $W$ g of $NaOH$ are needed.

$\text{Percent by mass}=\frac{\text{Mass of NaOH}}{\text{Mass of solution}}\times 100$

$\text{5}=\frac{\text{W}}{\text{100}}\times 100$

$W=\text{5 g}$