Arrange the following halomethanes in decreasing order of their dipole moment: CH ₃ F , CH ₃ Cl , CH ₃ Br and CH ₃ I .

Step-by-step solution

The dipole moment of a molecule is the product of the magnitude of the charge and the distance of separation ( = q d ). Although fluorine is more electronegative than chlorine, the C-Cl bond length is significantly larger than the C-F bond length. The increase in distance ( d ) for CH ₃ Cl outweighs the higher charge separation ( q ) in CH ₃ F . As a result, the dipole moment of CH ₃ Cl (approximately 1.86 D) is greater than that of CH ₃ F (approximately 1.84 D). For the remaining halogens, the sharp decrease in el