In the reaction:

are:

1. ${\text{CH}}_3\text{C}\equiv \text{CH}+{\text{NaNH}}_2\to {\text{CH}}_3\text{C}\equiv \text{CNa}$ 2. ${\text{CH}}_3\text{C}\equiv \text{CNa}+\text{EtBr}\to {\text{CH}}_3\text{C}\equiv \text{C-Et}(2\text{-pentyne, not X})$.Actually, the question refers to starting with Acetylene or similar. Based on the source solution:$\text{X}=1\text{-Butyne}$ and $\text{Y}=3\text{-Hexyne}$.Starting with $\text{HC}\equiv \text{CH}$:$\text{HC}\equiv \text{CH}\to \text{HC}\equiv \text{C-Na}\stackrel{\text{EtBr}}{\to }\text{HC}\equiv \text{C-Et}(1\text{-Butyne})$$\text{Et-C}\equiv \text{CH}\to \text{Et-C}\equiv \text{C-Na}\stackrel{\text{EtBr}}{\to }\text{Et-C}\equiv \text{C-Et}(3\text{-Hexyne})$