(a) how is a mixture of two organic compounds separated, which have different solubilities in the ame solvent?
(b) How is an organic liquid purified which decomposes below its boiling point?
(c) Why is sodium extract boiled with `HNO_3` before testing for halogens?
(d) What type of organic compounds cannot be estimated by Kjeldahl's method?
(e). What does blood-red colouration during Lassaigne's test indicate?
(f). What happens when `AgNO_3` solumtion is added to bromo methane?

Explanation

(a) by fractional crystallisation.
(b) Distillation under reduced pressure, i.e., vacuum distillation.
(c) to decompose `NaCN` or `Na_2S` present in the Lassaigne's extract, otherwise these will produce white precipitate with `AgNO_3` and thus interfere with the test of halogens.
(d) Compounds containing `N` in the ring and those compounds in which `N` atoms is directly linked either at an `O` atoms or another `N` atom such as in azo `(-N=n-)` and nitro `(-NO_2)` compounds.
(e). It indicates the presence of both N and S
(f). It would not give pale yellow precipitate of `AgBr` because `CH_3Br` is a convalent compound and hence does not contain `Br^(-)` ion. To get the precipitate of `AgBr`, `CH_3Br` is treated first with aqueous `KOH` to get `CH_3OH` and `Br^(-)` and then the addition of `AgNO_3`. It would now give the precipitate of `AgBr` partly soluble in `NH_3` or `NH_4OH`