2K(s) + 2H2O(l) = 2KOH(aq) + H2(g)
Potassium (K) is a group 1 metal, which is a solid.
Water (H2O) reacts with Potassium to form Potassium Hydroxide (KOH) and Hydrogen (H2).
Hydrogen exists naturally as a diatomic molecule and is usually a gas at room temperature, so it is written as H2(g).