An optically inactive compound [A] of mollecular formula `C_(4)H_(11)N` on treatement with nitrous acid gives an alcohol [B] which on heating with excess of concentrated sulphuric acid at 440 K gives an alkene [C]. The alkene [C] on treatment with `HBr` gives an optical compound [D] of molecular formula `C_(4)H_(8)Br`. Identify [A], [B], [C] and [D].

Explanation

`[A]" "underset("Butan-1-amine")(CH_(3)CH_(2)CH_(2)CH_(2)NH_(2))`
`[B]" "underset("Butan-1-ol")(CH_(3)CH_(2)CH_(2)CH_(2)OH)`
`[C]" "underset("But-2-ene")(CH_(3)CH=CHCH_(3))`
`[D]" "underset("2-Bromobutane")(CH_(3)underset(Br)(C)HCH_(2)CH_(3))`