Question

how many grams of 5%NaNO3 will be required to prepare 250ml solution

Answer 1

What kind of percent? Is this w/v, w/w, of just what. I will assume it is 5% w/v which means 5 g NaNO3/100 mL soln; therefore, for 250 mL (2.5 x 100) you will need 2.5 x 5 or 12.5 g NaNO3.