Which is true of hydroxide ions
a- they contain two hydrogen atoms
b- they dissociate to form protons
c- they have a negative charge
d- they are not found in pure water

Option (C) is the correct answer.

Explanation:

A hydroxide ion is an ion that has -1 charge and contains an oxygen and hydrogen atom together.

So, basically a hydroxide ion is ion.

Where as a hydrogen ion is defined as the ion in which a hydrogen atom holds a positive charge, that is, .

A proton is a sub-particle present inside the nucleus of an atom and it holds a positive charge. Symbol of proton is .

Thus, we can conclude that the statement they have a negative charge, is true of hydroxide ions.

the awnser is group 12