Alkynes

. Alkynes are catalytically hydrogenated to produce cis-alkene, which is then further hydrogenated in the presence of platinum to produce meso-2,3-dideuterobutane. The conversion of is the net response of C≡C to C-C with the addition of two molecules of H₂ and D₂

Alkynes may be hydrogenated by simply adding hydrogen atoms across their triple bonds. Alkane results from the formation of a carbon-carbon double bond, while alkene results from the formation of a carbon-carbon single bond.

A bond will be lost if hydrogen atoms are added across a double bond.

The result of hydrogenating the provided alkyne is

Furthermore, the double bond in cis-2-butene is broken down into a single bond and an alkane is produced when deuterium is added in the presence of a platinum catalyst.

Meso compounds are substances that contain a centre of symmetry and are optically active, meaning they exhibit a non-superimposable mirror image.

A racemic mixture is a collection of substances with both a (R) and a (S) structure.

The compound produced cannot be a racemic combination because it displays optical activity.

The resultant product is a meso compound in this case because it possesses a plane of symmetry and a non-superimposable mirror image that makes it optically active

So, the correct answer is cis-butene-2 and meso-2,3-dideuterobutane.