Question

addition of H2/Ni is a type of syn addition or trans addition ​

Answer 1

Answer:

Using any transition metal catalyst (Pt, Pd, Ni) for hydrogenation of alkynes results in syn hydrogenation to not alkenes but alkanes. Using Lindlar's catalyst results in syn hydrogenation of an alkyne to an alkene.

In the case of sodium metal (not a transition metal) in ammonia, hydrogenation of alkynes results in a trans alkene.

Answer 2

Answer:

Using any transition metal catalyst (Pt, Pd, Ni) for hydrogenation of alkynes results in syn hydrogenation to not alkenes but alkanes. Using Lindlar's catalyst results in syn hydrogenation of an alkyne to an alkene.

Explanation: