Answer:
XY bond is the least polar
Explanation:
Given
[tex]W = 1.0[/tex]
[tex]X = 2.0[/tex]
[tex]Y = 2.5[/tex]
[tex]Z = 3.5[/tex]
Required
The least polar bond
First, we calculate the difference in the electronegativities
[tex]WX = X - W[/tex]
[tex]WX = 2.0 - 1.0[/tex]
[tex]WX = 1.0[/tex]
[tex]WY = Y - W[/tex]
[tex]WY =2.5 - 1.0[/tex]
[tex]WY =1.5[/tex]
[tex]WZ =Z-W[/tex]
[tex]WZ =3.5 - 1.0[/tex]
[tex]WZ =2.5[/tex]
[tex]XY = Y -X[/tex]
[tex]XY = 2.5 -2.0[/tex]
[tex]XY = 0.5[/tex]
[tex]XZ = Z -X[/tex]
[tex]XZ = 3.5 -2.0[/tex]
[tex]XZ = 1.5[/tex]
[tex]YZ = Z - Y[/tex]
[tex]YZ = 3.5 - 2.5[/tex]
[tex]YZ = 1.0[/tex]
The least of the above calculations will be the least polar.
Hence, XY is the least polar