if the normality of a solution of Ba(OH)2 is 4.0, what is the molarity?

Answer 1

The molarity of Ba(OH)2 is half the normality, so the answer is 2.0; each molecule of Ba(OH)2 produces 2 OH- ions, so there will be twice as many OH- ions in solution as there are (were) Ba(OH)2 molecules.