Which two reactions are faster than the others? Silver tarnishes in air that contains hydrogen sulfide.
Iron metal reacts with oxygen in air to form rust.
Lead nitrate and potassium iodide react to form a yellow precipitate.
Lead nitrate and potassium iodide react to form a yellow precipitate.

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged

Ibelieve the answer 4 moles

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.