Calculate the molarity of each of these solutions.
a. A 5.623-g sample of NaHCO3 is dissolved in enough water to make 250.0 mL of solution.
b. A 184.6-mg sample of K2Cr2O7 is dissolved in enough water to make 500.0 mL of solution.
c. A 0.1025-g sample of copper metal is dissolved in 35 mL of concentrated HNO3 to form Cu2 ions and then water is added to make a total volume of 200.0 mL. (Calculate the molarity of Cu2.)