Show calculations (labeled with units) needed to prepare 25 mL of 0.20 M Pb(NO3)2 and 25 mL of 0.20 M NaI.
Both are done the same way. Here is how to do the first one.
How many mols do you need? That's
mols = M x L = ?
Then mols = g/molar mass. You know molar mass and mols, solve for grams Pb(NO3)2 or NaI needed.