How many grams of NaOH are needed to make 450mL of a 2.5%(m/v) NaOH solution?

Answer 1

2.5% m/v means 2.5 g NaOH per 100 mL solution.
So you want 2.5 g for 100 mL, how much will you need for 450 mL. That is
2.5 x (450/100) = ?

Or you can plug it into the formula of
%m/v = (g solute/mL solvent)*100 = (g solute/450)*100 = 2.5% and solve for g solute.