Question

Is H3O+ polar or non polar? (explain please.)?

Answer 1

The overall molecule is Polar because the shape of the molecule is Trigonal Pyramidal, which means it has the lone pair electrons. Becuase of the lone pair the pulling is unequal.   

H3O+ has 3 polar bonds. 
To know if the bonds are polar or nonpolar find the difference of the element's electronegativity charge. 
H has electronegativity charge of 2.2, and O has 3.4.
Always subtract the smaller number from the greater one. 
So 3.4 - 2.2 = 1.2 
If the difference is from 0-0.4 the bond is nonpolar, but if it's from 0.5-1.9 the bond is polar. 
So, 1.2 is polar bond. So H3O+ has 3 polar bonds, and the overall molecule is polar too. 

A simple way to know if it's polar or nonpolar is to draw the lewis dot structure, and use VSEPR.