Which statements about permanganate titrations are correct?

A $HCl$ is a suitable acid for the titration because chloride ions are not oxidised by permanganate.
BIn the titration with oxalic acid the solution is warmed initially because the reaction is slow at room temperature.
CThe end point is a pale pink colour that persists for about half a minute.
D $KMnO X_{4}$ is not a primary standard, so its solution is standardised against oxalic acid or Mohr's salt.

Answer: B, C, D

Permanganate solutions contain

MnO X_{2}

and decompose slowly, so they are standardised. The oxalate reaction is slow at first (warming and autocatalysis by

Mn X^{2 +}

). Chloride is oxidised by permanganate, so

HCl

must not be used.