[" A gas decolourised by "KMnO_(4)" solution but gives no "],[" precipitate with ammoniacal cuprous chloride is "]

A colourless compound X on treatment with alc. KOH gave a gaseous compound Y. The compound Y decolourises bromine water and alkaline KMnO_(4) solution but gives no precipitate with ammoniacal cuprous chloride. The compound X is :

A hydrocarbon with five carbon atoms in the molecule decolourises alkaline 'KMnO_4', but does not give precipitate with ammoniacal cuprous chloride solution. The hydrocarbon is, an alkene a haloalkene an alkyne an alkane

A gas decolourises KMnO_4 but does not give any precipitate with ammoniacal AgNO_3 . The gas is :

Acetylene reacts with ammoniacal cuprous chloride to from :