Aqueous solution of $\mathrm{A}+\mathrm{AcOH}+{\mathrm{K}}_2{\mathrm{CrO}}_4\to$ yellow ppt. The above information is incorrect for which of the following cations?

(P) ${\mathrm{Pb}}^{+2}$ (Q) ${\mathrm{Ba}}^{2+}$ (R) ${\mathrm{Ca}}^{2+}$ (S) ${\mathrm{Sr}}^{2+}$

$\mathrm{Pb}+2+\mathrm{AcOH}+{\mathrm{K}}_2{\mathrm{CrO}}_4\to$yellow precipitate

${\mathrm{Sr}}^{2+}+\mathrm{AcOH}+{\mathrm{K}}_2{\mathrm{CrO}}_4\to$yellow precipitate

The elimination of heavy metals from water, such as lead, copper, or zinc, is another excellent application of precipitation.

By adding an extra amount of ammonium oxalate to the boiling solution and titrating the results with standard permanganate, strontium can be precipitated. As a result, lead and strontium ions give a yellow precipitate with acetic acid and potassium dichromate.