Question

1. what are produced when a base is mixed with water?

a. hydrogen ions
b. hydroxide ions
c. oxygen atoms
d. oxygen ions

Explanation:

When a base is mixed with water, it dissociates to produce hydroxide ions ($\ce{OH-}$). Hydrogen ions ($\ce{H+}$) are produced by acids. Oxygen atoms and oxygen ions are not the characteristic products of bases in water.

Answer:

B. hydroxide ions