When a metallic oxide is dissolved in water, the solution formed has a high concentration of ________. ions (${H^ + }$ , ${H_3}{O^ + }$ , $O{H^ - }$)

Hint: Metallic oxides are crystalline solids that contain an oxide ion and a metal cation. When they are dissolved in water they form salts that release hydroxide ions. A metallic oxide is basic.

Complete step by step answer:
When a metallic oxide is dissolved in water then the solution which is formed has a high concentration of hydroxide ion. Those kinds of solutions are basic. Let’s take an example
When sodium oxide is dissolved in water it forms sodium hydroxide. The solution is basic and it liberates a large number of hydroxide ions. The reaction taking place is as follows

$N{a_2}O + {H_2}O \to 2NaOH$

Also, it dissociates in water to give hydroxide ions

$NaOH \to N{a^ + } + O{H^ - }$

So the solution formed when a metal oxide is dissolved in water has the highest concentrations of hydroxide ion.

So, the correct answer is $O{H^ - }$ an ion.

Additional Information:
Metal oxides are basic because they react with dilute acid to form salt and water. Also not all metal oxides are basic, some are amphoteric, that is they react with both base and acid. Some examples of amphoteric oxides are $A{l_2}{O_3}$ , $ZnO$ , $Ti{O_2}$ and ${V_2}{O_5}$.

Note: Metal oxides are crystalline solids which contain a metal cation and an oxide anion. Both alkali metal oxides and alkaline earth metal oxides are ionic and react with water to form basic solutions of the metal hydroxide. The reaction taking place is as follows

${M_2}O + {H_2}O \to 2MOH$ where M is group one metal

Also $MO + {H_2}O \to M{(OH)_2}$ where M is group two metal