What do all acids and bases have in common?

- Hint: Acids and bases produce ions when they are dissolved in water. The ions move freely around in the water.

Complete step-by-step solution -

Let us see the similarities of acid and bases in details:
All acids and bases are made up of ions. Acids are mainly made up of hydrogen ions and a non-metallic anion. Bases are mainly made up of hydroxyl ions and a metallic cation.
So, as we can see that both acids and bases are made up of ions and thus they are electrolytes. Electrolytes produce ions when dissolved in a polar solvent and make it a conducting solution.
Thus, acid and bases both can conduct electricity with the help of free ions they produce when dissolved in water. The acids release ${ H }^{ + }$ ions in water and the bases release ${ OH }^{ - }$ ions in water.

Additional Information:
Pure water is a non-electrolyte i.e. it cannot conduct electricity under normal circumstances. But when we add a different electrolyte to pure water, it can conduct electricity easily. The electrolyte added to pure water for this process is usually acid or base. When acid or base is added to the water, the anion present in the acid or base attracts the ${ H }^{ + }$ ion of water and the cation present in the acid or base attracts the ${ OH }^{ - }$ ions of water. In this way the water becomes conductive.

Note: There are some acids like ${ BF }_{ 3 }$ and bases like ${ NH }_{ 3 }$ which do not have ${ H }^{ + }$ or ${ OH }^{ - }$. They fall under the category of Lewis acid and base. A Lewis acid is one that can accept a pair of electrons while a Lewis base is the one that donates a pair of electrons.