The dipole of CCl₄, CHCl₃ and CH₄ are in the order :

Solution

Chemistry ma’am · 4 steps

Do not compare bond polarities first; look at the shape and see whether the bond dipoles cancel.

1. Same shape. All three molecules are tetrahedral around carbon, with bond angles close to 109.5°. The net dipole moment is the vector sum of the four bond dipoles.
2. Symmetric ones cancel. In CH₄ and CCl₄, all four bonds are identical and point to the corners of a regular tetrahedron. The four equal bond dipoles cancel exactly, so both have μ = 0, even though each C-Cl bond is quite polar.

   Molecule	Four bonds	Do the bond dipoles cancel?	Net dipole
   CH₄	4 identical C-H	yes	0
   CCl₄	4 identical C-Cl	yes	0
   CHCl₃	3 C-Cl and 1 C-H	no, the bonds are unequal	about 1.0 D

3. Chloroform does not cancel. In CHCl₃, one C-H bond replaces a C-Cl bond. The bonds are no longer equal, the symmetry is broken and a net dipole remains.
4. So. The order is CH₄ = CCl₄ < CHCl₃, which is option (b).

The idea to keep. Polar bonds do not guarantee a polar molecule. If identical bonds sit in a symmetric shape (linear, trigonal planar, tetrahedral), the dipoles cancel and μ = 0.

Answer from the NTA final answer key. Solution by PrepWiser.