When a liquid freezes and then melts the steps are exothermic?

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

Can someone me with 1 to 4 plz. fast

16. in a reaction that has reached equilibrium, a. the forward and reverse reactions are occurring at the same rate. b. the reactants and products are in equal concentrations. c. the forward reaction has gone further than the reverse reaction. d. there are equal numbers of atoms on both sides of the equation. e. a, b, and d are correct.