Which of the following statement(s) is/are correct with respect to bromide ions ?
A. KBr on heating with `MnO_(2)` and concentrated `H_(2)SO_(4)` liberates `Br_(2) " and" SO_(2)` gases.
B. KBr on heating with concentrated `H_(2)SO_(4)` liberates `Br_(2) " and" SO_(2)` gases.
C. KBr forms HBr with concentrated `H_(3)PO_(4)`.
D. KBr(s) liberates `Br_(2)` on gentle warming with concentrated `H_(2)SO_(4)` and `K_(2)Cr_(2)O_(7)`(s).