A `2.0mL` sample of a colourless solution, when treated with a few drops of `2M` hydrochloric acid, forms a while precipitate which dissolves when the solution is heated to boiling. The original solution could have contained which of the following cations?
(P) `0.1M Ag^(+)` (Q) `0.1M Pb^(2+)`
A. P only
B. Q only
C. Either P or Q
D. Neither P nor Q
