Ammonia, water and ClBr are polar while acetylene is nonpolar.
What is a polar molecule and nonpolar molecule
A polar molecule is one in which the electric charge is separated due to an unequal distribution of electrons. This happens when there is an uneven distribution of electrons due to the atoms' varying electronegativities within the molecule.
A molecule with a symmetrical distribution of charge is said to be nonpolar when its atoms share the same number of electrons. This usually happens when the electronegativities of the atoms in the molecule are similar.