Part A - Noble Gases are generally nonreactive. Part B - Alkali metals are very reactive metals that react violently when dropped in water. Part C - Alkaline earth metals are fairly reactive metals that react with water, but not explosively like the alkali metals. Part D - Halogens are highly reactive but are nonmetals.
Work Step by Step
Noble gases are extremely non-reactive due to their full valence shells. Alkali metals are extremely reactive and easily lose their single valence electrons to become cations. Alkaline earth metals are somewhat reactive and become more so as you move down the group to the heavier elements. Halogens are very reactive nonmetals with seven valence electrons that also react strongly with water.