Check all items common to bases.

minerals

metal

gas

H+

OH-

nitrogen

OH - is common to bases.

Explanation:

The base is a is an ionic compounds which when placed in aqueous solution dissociates in to a cation and an anion OH-.

The presence of OH - in the solution shows that the solution is basic or alkaline.

From Bronsted and Lowry concept base is a molecule that accepts a proton for example in NaOH, Na is a proton donor and OH is the proton acceptor.

A base accepts hydrogen ion and the concentration of OH is always higher in base.

There is a presence of conjugate acid and conjugate base in the Bronsted and Lowry acid and base.

Conjugate acid is one which is formed when a base gained a proton.

Conjugate base is one which is formed when an acid looses a proton.

And from the Arrhenius base Theory, the base is one that dissociates in to water as OH-.