Finely ground nickel (II) hydroxide is placed in a beaker of water. It sinks to the bottom of the beaker and remains unchanged. An aqueous solution of hydrochloric acid is then added to the beaker and the Ni(OH)2 disappears. Which reaction best describes what occurred in the beaker?

Your answer:

Ni(OH)2 (s) + HCl (aq) → NiO (aq) + H2 (g) + HCl (aq)

Ni(OH)2 (s) + 2 HCl (aq) → NiCl2 (aq) + 2 H2O (l)

Ni(OH)2 (s) + 2 H2O (l) → NiCl2 (aq) + 2 H2O (l)

Ni(OH)2 (s) + 2 H2O (l) → NiCl2 (aq) + 3 H2O (l) + O2 (g)