Answer
The IUPAC name of the compound is $4-phenylpent-2-yne$
Work Step by Step
The compound has 5 carbon atoms in its longest carbon chain containing the triple bond(pent−). It has a $phenyl$− substituent at position 4, and a triple bond at position 2. So, the IUPAC name of the alkene is $4-phenylpent-2-yne$