Which of the following statements `"is"//"are"` correct?

Options

A. In Lassaigne's test for halogens, conc. `HNO_(3)` is used to remove HCN and `H_(2)S`
B. When an organic compound is heated with dry CuO and the gases evolved are passed through lime water which turns milky, the gas may be `CO_(2)` or `SO_(2)`
C. In Carius method, sulphur is oxidised to `SO_(4)^(2-)` ion with fuming `HNO_(3)`
D. In Lassaigne's test, N present in the organic compound is converted into CN-'' ions

Answer

A, B, C, D

Explanation

a) = Conc. -`HNO_(3)` removing `CN^(-), S^(-2)`, other wise these ions also giving test with `AgNO_(3)` solution
b) White precipitation due to formation of `CaCO_(3)` or `CaSO_(3)`
c) Due to oxidizing power of Conc. `HNO_(3)`
d) Due to oxidizing power of Conc. `HNO_(3)`