Pls help with science

Which substances have the lowest melting points: ionic covalent, or metallic

Which of the following statements about acidic water is true? a. acid has no effect on the h,o molecules. b. the solution contains a larger number of oh ions than h,o ions. c. the solution contains a larger number of h,o ions than qh ions. d. the solution contains an equal number of h,o ions and oh ions. none of the above e.

0.09 moles of sodium sulfate in 12 ml of solution