Question

What contains more `OH`- ions?

Answer 1

Bases, or salts that are basic in nature in aqueous solutions.

Explanation:

Bases on being dissolved in water ionise (or dissociate) to form OH- ions.

Weak base ionise partially, with only few OH- ions in the aqueous solutions.
Strong bases ionise completely, with large number of OH- ions present in the aqueous solutions of that base.
Some salts which are basic in nature also dissociate into OH- ions in water.

Please note: Acids also liberate OH- ions in their aqueous solutions due to ionisation of water, but these are in negligible quantities.

Strong bases include NaOH and KOH
Weak bases include Mg(OH)2 and Ca(OH)2
An example of a salt basic in nature is Na2CO3

Hope this helps :)