Select all correct statements about the oxalate ion in qualitative analysis.

AIt decolourises hot, acidified $KMnO X_{4}$ solution.
BBoth gases evolved with concentrated $H X_{2} SO X_{4}$ turn lime water milky.
CWarming its salt with concentrated $H X_{2} SO X_{4}$ gives $CO$ and $CO X_{2}$ in equal moles.
DWith aqueous $CaCl X_{2}$ it gives a white precipitate that is insoluble in acetic acid but dissolves in dilute HCl.

Answer: A, C, D

2 MnO X_{4} X^{-} + 5 C X_{2} O X_{4} X^{2 -} + 16 H X^{+} 2 Mn X^{2 +} + 10 CO X_{2} + 8 H X_{2} O

decolourises the permanganate.

CaC X_{2} O X_{4}

is white, insoluble in acetic acid and soluble in strong acid. Conc.

H X_{2} SO X_{4}

gives

CO

and

CO X_{2}

in a 1:1 ratio, but CO does not turn lime water milky, so the last statement is false.