Question

A solution with weight percentage of sodium hydroxide of 9% is prepared by adding the following mass of water (in grams) to 300 grams of that solution with a weight percent of $NaOH$ of 15%.

Answer 1

wt % of $NaOH=$ 15% (Initial)

wt % of $NaOH=g$% (final)

Initial solution $=300$ gm

wt of $NaOH$ $=$ $\frac{15}{100}\times 30=45$g

for making it to $g$%

$g=\frac{45}{x}\times 100=500$ g

Amount of water added = 200 g