Final answer:
The dipole moment of a molecule depends on the electronegativity difference and bond length. F2O has the lowest dipole moment, followed by Cl2O and H2O. HF has the highest dipole moment, followed by HCl, HBr, and HI.
Step-by-step explanation:
The dipole moment of a molecule depends on both the electronegativity difference of the bonded atoms and the bond length. In general, a higher electronegativity difference and a longer bond length will result in a higher dipole moment. To determine the order of decreasing dipole moment for the linear molecules F2O, H2O, and Cl2O, we need to consider the electronegativity difference between the atoms in each molecule. The electronegativity of oxygen is higher than that of fluorine, chlorine, and hydrogen. Therefore, F2O will have the lowest dipole moment, followed by Cl2O, and then H2O.
For the second part of the question, we need to consider the electronegativity difference and bond length for the linear molecules HI, HBr, HCl, and HF. The electronegativity of fluorine is higher than that of chlorine, bromine, and iodine. Therefore, HF will have the highest dipole moment, followed by HCl, then HBr, and finally HI.