Which one of the following pairs of solution is not an acidic buffer ?

The K_sp of Ag₂CrO₄,  AgCl,  AgBr  and Agl  are respectively, 1.1 $$ \times $$ 10^$$-$$12, 1.8 $$ \times $$ 10^$$-$$10, 5.0 $$ \times $$ 10^$$-$$13, 8.3 $$ \times $$ 10^$$-$$17. Which one of the following salts will precipitate last if AgNO₃ solution is added to the solution containing equal moles of NaCl, NaBr, Nal and Na₂CrO₄?

Which of the following salts will give highest pH in water?

Accumulation of lactic acid (HC₃H₅O₃), a monobasic acid in tissues leads to pain and a feeling of fatigue. In a 0.10 M aqueous solution, lactic acid is 3.7% dissociates. The value of dissociation constant, K_a, for this acid will be