Question

calculate amount of water in gram required to prepare 20 percent NaOH solution​

Answer 1

20% NaOH (W/V), means 20 grams of NaOH solids, dissolved in distilled water until you have 100mL of aqueous solution. Do this in beaker slowly, and drip water until it reaches exactly 100 mL mark. 20% NaOH(W/W) means 20 grams of NaOH solids plus 80 grams of distilled water, making up 100 grams of solution.