2) A sample solution is given to you that may contain any or all of the following ions : Ag⁺, Pb²⁺, and Ni²⁺. In an attempt to determine which cations are present, you add the following solutions. You found that no precipitate formed when either an aqueous solution of NaCl or an aqueous solution of Na₂SO₄ was added to the sample solution. However, a precipitate did form when you treated the sample solution with a basic solution of NaOH. Which cation or cations are present in the sample?

Give your reasoning.

3) Balance the following redox reaction. Identify the oxidizing and reducing agents, and the substances oxidized and reduced.

(a) Al_(s) + NO₂^-_(aq) --> AlO₂^-_(aq) + NH_3(aq) +NH_3(aq) in basic solution.

(b) H₂SO_3(aq) + MnO₄^-_(aq) -->Mn²⁺_(aq) + HSO₄^-_(aq) in acidic solution.