What is the molarity of sodium ions in a 0.796 M Na2SO4 solution?

Which of the following is a compound? a. carbon b. oxygen c. hydrogen d. water

Define dew point. i am writing this part to be able to ask the question

An excess of lithium oxide undergoes a synthesis reaction with water to produce lithium hydroxide li2o+h2o→2lioh if 1.05 g of water reacted, what is the theoretical yield of lithium hydroxide? a) 5.83 x 10–2 g lioh b) 1.17 x 10–1 g lioh c) 2.79 x 100 g lioh d) 1.40 x 100 g lioh