Crt option C.
NH3 has higher dipole moment than NF3 . » REASON: in case of NH3, nitrogen is more electronegative than hydrogen,so it tries to pull the electrons from hydrogen atoms. where as in case of NF3, fluorine being more electronegative than nitrogen tries to pull the electrons from nitrogen opposite from that of nitrogen.

Answer:

To determine the molecule with the maximum dipole moment among CO2, CH4, NH3, and NF3, we need to evaluate the polarity of each molecule. Dipole moment is a vector quantity that measures the separation of positive and negative charges in a molecule. It depends on the electronegativity difference between the atoms and the molecular geometry.

1. CO2:
CO2 has a linear molecular geometry due to its central carbon atom being bonded to two oxygen atoms. Oxygen is more electronegative than carbon, resulting in a polar bond between carbon and each oxygen atom. However, the molecule as a whole is nonpolar because the bond dipoles cancel each other out. Therefore, CO2 has zero dipole moment.

2. CH4:
CH4 has a tetrahedral molecular geometry with the carbon atom at the center and four hydrogen atoms surrounding it. Carbon and hydrogen have similar electronegativities, so the C-H bonds are nonpolar. Additionally, the molecule is symmetrical, with all bond dipoles pointing towards the center, thereby canceling out each other. Hence, CH4 has zero dipole moment.

3. NH3:
NH3 has a trigonal pyramidal molecular geometry with the nitrogen atom at the center and three hydrogen atoms and a lone pair of electrons surrounding it. Nitrogen is more electronegative than hydrogen, creating polar N-H bonds. The molecule is also unsymmetrical due to the presence of the lone pair. The lone pair causes a distortion in the electron cloud around the nitrogen atom, resulting in a net dipole moment. Thus, NH3 has a dipole moment.

4. NF3:
NF3 has a trigonal pyramidal molecular geometry similar to NH3, with the nitrogen atom at the center and three fluorine atoms surrounding it. Fluorine is highly electronegative, and nitrogen is moderately electronegative. Therefore, the N-F bonds are polar. The molecule is also unsymmetrical due to the presence of the lone pair on nitrogen. The dipole moments of the N-F bonds do not cancel each other out, resulting in a net dipole moment. Thus, NF3 has a dipole moment.

Conclusion:
Among the given molecules, NH3 and NF3 have dipole moments, while CO2 and CH4 have zero dipole moments. However, to determine which molecule has the maximum dipole moment between NH3 and NF3, we need to consider the electronegativity difference. Since fluorine is more electronegative than nitrogen, the N-F bonds in NF3 are more polar than the N-H bonds in NH3. Therefore, NF3 has a higher dipole moment than NH3. Thus, the molecule with the maximum dipole moment among CO2, CH4, NH3, and NF3 is NF3.