What happens to the hydronium ion (H3O+) concentration when hydroxide ions are added to water? 1. The hydronium concentration decreases because hydronium ions get used up to make water and reduce the extra hydroxide ions.

2. The hydronium concentration increases proportionately with the hydrogen concentration.

3. The hydronium concentration remains constant because it is in equilibrium.

4.The hydronium concentration increases to a higher pH.​

Answerthe half-reaction having the greatest tendency to occur at the anode:     i₂(aq) + 2e⁻  ⇄ 2i⁻  ;   e = +0.53 v======oxidation occurs at the anode. we must therefore find the half-reaction with the greatest tendency to oxidize.the given values of e are reduction potentials (the form of the half-reactions are of reduction).the lower the reduction potential, the higher the potential to oxidize. the half-cell with the lowest reduction potential will have the greatest tendency to oxidize at the anode.the half-reaction having the greatest tendency must be    i₂(aq) + 2e⁻  ⇄ 2i⁻    e = +0.53 vbecause its reduction potential is the lowest out of the three.