How will you distinguish between ?
(i) Diethyl ether and n-butane (alkane).
(ii) Diethyl ether and but-1-ene(an alkene).
(iii) Diethyl ether and alcohol (primary).
(iv) An ether and alkyl bromide.

Explanation

[Hint]
(i) Diethyl ether dissolves in concentration `H_(2)SO_(4)` forming
`C_(2)H_(5)-O-C_(2)H_(5)rarr [underset("Oxanium salt")(C_(2)H_(5)-underset(+)overset(H)overset(|)(O)-C_(2)H_(5))]HSO_(4)^(-)`
n-Butane does not react with `H_(2)SO_(4)` and thus, two distinct laers are formed when `H_(2)SO_(4)` is added to n-butane.
(ii) But-1-ene decolourises alkaline potassium permanganate solution .
`underset("But-1-ene")(CH_(3)CH_(2)CH)=CH_(2)+H_(2)O+[O]rarr underset("Butane -1,2-diol")(CH_(3)CH_(2)CHOHCH_(2)OH)` ltbr. Diethyl ether does not decolourises `KMnO_(4)` solution.
(iii) Ethyl alcohol produces hydrogen (bubbles) when reacted with sodium. Ether does not react with sodium.
(iv) The ether dissolves in conc. `H_(2)SO_(4)` , the halide does not Alkyl bromide forms a light yellow precipitate of AgBr when treated with alcoholic `AgNO_(3)`. This test is not given by ether.