Determine whether each of the molecules below is polar or nonpolar. Tetrahedral C C l 4 CClX4 Nonpolar Tetrahedral C H 3 O H CHX3OH Polar Trigonal pyramidal N H 3 NHX3 Nonpolar Linear C S 2 CSX2 Nonpolar

CCl4 - Nonpolar

CH3OH - polar

NH3 - polar

CS2 - Nonpolar

Explanation:

One important thing that we should know is that polarity has to do with the presence of a resultant dipole moment in a molecule.

Dipole moment is a vector quantity, This means that its direction is also taken into account when discussing the dipole moment of molecules.

Hence, symmetrical molecules such as CS2 and CCl4 are non-polar even though they have polar bonds because their dipoles cancel out(zero resultant dipole moment).

On the other hand, NH3 and CH3OH are non-symmetrical molecules hence they possess an overall dipole moment and are polar molecules.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.