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.
Since there is no loss of any particle to vapor during the phase change process from solid to liquid, the mass of the before and after the process will remain the same.
In this way, the law of conservation of mass is obeyed.
Mass is the amount of matter contained in a substance.
Since there is no room for escape or matter loss, the mass will remain the same.
