PAC name is Pent-2-yne.
Step 1: Find the longest continuous carbon chain. Here the longest chain has 5 carbons (Root word: Pent)
Step 2: Identify and name the groups that are attached to this chain. Here one triple bond is present on the chain.
Step 3: Numbered the chain consecutively, starting at the end nearest a substituent group.
Step 4: Designated the location of each substituent group by an appropriate number and name. Here one triple bond is present on the chain at 2nd position.