the compound contains 6 Carbon atoms, its said to be an alkyne therefore compound should contain a triple bond.
There should be single C as chiral centre. This means that one carbon has 4 different groups attached to it. In the diagram shown has one carbon connected to
1- Hydrogen
2 - CH3 group
3 - C2H5 group
4 - C≡CH
All these groups are of different types, hence the C is a chiral centre .
