Which of the following molecules contain(s) a polar bond?

Question

Quizplus · Accepted Answer

A polar bond is defined as a covalent bond in which there is an unequal sharing of electrons between the two atoms involved in the bond, resulting in a partial positive charge on one atom and a partial negative charge on the other atom. 
In molecule I, there is a polar covalent bond between the oxygen (O) and hydrogen (H) atoms in the hydroxyl (OH) functional group. 
In molecule II, there are two polar covalent bonds between the oxygen (O) and hydrogen (H) atoms in the two hydroxyl (OH) functional groups. 
In molecule III, there is a polar covalent bond between the nitrogen (N) and hydrogen (H) atoms in the amino (NH2) functional group. 
In molecule IV, there are no polar covalent bonds, as all the bonds are between atoms of the same element (carbon-carbon and carbon-hydrogen bonds). 
In molecule V, there is no polar covalent bond, as the only bond is between two carbon (C) atoms.

Which of the Following Molecules Contain(s) a Polar Bond