Where, approximately, is the negative pole on each of these
molecules?
Answer
General guidance
The atoms in the molecule show positive and negative poles. The positive pole represents that the atom is the least electronegative and the negative pole represents that the atom is the most electronegative.
Example:
In Hydrogen bromide
, bromine 
is more electronegative than hydrogen. In this molecule, the positive pole is hydrogen and the negative pole is bromine. The electrons in the bonded atoms move to a more electronegative site.
Step-by-step
Step 1 of 3
Consider the structure of compound as shown below:
In this molecule, one oxygen, one carbon and two fluorine atoms are present. In general, oxygen atom is less electronegative than fluorine atom therefore, C-O bond is less polar than C-F bond. Therefore, the negative pole will not present towards the 
atom.
Since, both the fluorine atoms are pulling the electrons from C equally in a common direction thus, the resultant negative pole will be present I between the two F atoms.
The negative pole on these molecules will be present:
The given molecule consists of carbon, oxygen and 2 fluorine atoms. Among these atoms, fluorine is more electronegative than carbon and oxygen. Hence, both the fluorine atoms attracts the bonding electron towards itself equally. Therefore, the negative pole will be present between two fluorine atoms.
Step 2 of 3
Consider the structure of compound as shown below:
This molecule contains one oxygen atom, one carbon atom, one hydrogen atom and one fluorine atom. In general, oxygen atom is less electronegative than fluorine atom therefore, C-O bond is less polar than C-F bond.
But both the polar bonds are not present in opposite direction thus they won’t cancel out each other effect instead both oxygen and fluorine atom are pulling the electrons from the carbon atom in a common direction thus, the resultant negative pole will be present between oxygen and F atom.
The negative pole on these molecules will be present:
The given molecule consists of carbon, oxygen, fluorine and hydrogen atoms. Among these atoms, fluorine and oxygen are more electronegative than carbon and hydrogen. Hence, fluorine and oxygen atoms attract the bonding electron towards themselves. Therefore, the negative pole will be present between fluorine and oxygen atoms as resultant dipole of the two bonds will be present in between the two atoms.
Step 3 of 3
Consider the resultant dipole moments in each compound as shown below:
Therefore, 
shows more dipole moment as polar bonds in 
nearly cancel out each other effect.
The molecule that shows a higher dipole moment:
Consider the bond moments and the resultant dipole moment in molecule as shown below:
In , resultant two dipole moments of the polar bonds are in opposite directions as shown with blue arrows thus, they would nearly cancel out each other effect.
Consider the individual bond moments and resultant dipole moment in molecule as shown below:
The molecule will show a higher dipole moment than as the two dipole of the polar bond in would give a resultant dipole moment in one direction and there is no other opposing dipole moment present in the compound to counter its effect. Here, C-H bond is considered as non-polar as there is very less electronegativity difference between C and H.
Therefore, shows more dipole moment as polar bonds in nearly cancel out each other effect.
Answer
The negative pole on these molecules will be present:
The negative pole on these molecules will be present:
The molecule that shows a higher dipole moment:
Answer only
The negative pole on these molecules will be present:
The negative pole on these molecules will be present:
The molecule that shows a higher dipole moment:
