Which term does not belong and explain why?

Question

1) hydrogen-ion concentration
hydroxide-ion concentration
basic solution
ion-product constant for water
Basic solution because all other terms refer to the quantity of the hydrogen and hydroxide ions.

2) basic
neutral
acidic
hydronium ion
Hydronium ion because all other terms describe different types of solutions and the concentrations of H+ and OH- and the nature of a substance.

3) acidic solution
hydroxide ion
basic solution
alkaline solution
Acidic solution because an alkaline solution is a basic solution and the hydroxide ion is dominant in alkaline/basic solutions.

4) pH
dissociation constant
hydronium ion
hydroxide ion
Dissociation constant because hydronium ion and hydroxide ion are related to pH.

Can someone tell me if my answers are correct and if the explanations are accurate? If they aren't accurate or don't make any sense, can you provide any suggestions? Thanks in advance.

Answer 1

They're fine. You could argue in 3 that hydroxide ion was the odd one out, because it hasn't got the word solution in it...!