What is the concentration (in % mass) of a solution in which you dissolve 200 mg of NaHCO3 in 1.0 L of water?

Answer 1

I don't know. But I can guess.
Since 200 mg is a rather small amount, it won't take up much volume, so the final volume of the solution will be VERY close to 1,000 mL and it will have a mass of VERY close to 1000 g.(actually 1000.2 g)
0.2 g/(1000.2)*100 = ??