Given the reactions:

2 X (s) + 2 H2O () → 2 X + (aq) + 2 OH - (aq) + H2 (g)

2 Y (s) + 2 H2O () → 2 Y + (aq) + 2 OH - (aq) + H2 (g)

The unknowns, X and Y, are most likely

A) metallic elements in the same group

B) metallic elements in the same period

C) nonmetallic elements in the same group

D) nonmetallic elements in the same period

A) metallic elements in the same group

Explanation:

X and Y are are group one elements called Alkali metals that react with water to displace hydrogen gas. They have large electrode potential thus they are oxidized to form a metal ion while the water is reduced to hydroxide ions and hydrogen gas. The solution formed is a basic solution and the reaction is exothermic. Note that the reaction of Alkali metals with water is violently and explosively.