A mixture of hept-1-yne, hept-2-yne, and hept-3-yne was hydrogenated in the presence of a platinum catalyst until hydrogen uptake ceased. If one assumes that the hydrogenation went to completion, how many different seven-carbon hydrocarbons were produced?

Only one seven carbon hydrocarbon was produced.

Explanation:

Alkynes are reduced completely in presence of to produce alkanes.Hydrogenation in presence of Pt is a simple nucleophilic addition process where molecule adds onto an unsaturated bond.Hept-1-yne, hept-2-yne and hept-3-yne are constitutionally isomeric to each other. Hence, after complete reduction, all three alkynes produced heptane as only product.So, only one seven carbon hydrocarbon was produced.