Answer :
The negative ion in aqueous sodium hydroxide, NaOH(aq) is hydroxide ion, OH-.
What is a neutralization reaction?
A neutralization reaction is a reaction between an acid and a base to form salt and water only.
The reaction between vinegar and NaOH is a neutralization reaction which produces a salt and water only.
NaOH is composed of a positive sodium ion, Na+ and a negative hydroxide ion, OH-
Therefore, the negative ion in the NaOH(aq) used in this titration is hydroxide ion, OH-.
Learn more about hydroxide ion at: https://brainly.com/question/3078877