Statement A: In NH3, the orbital dipole due to the lone pair is in the same direction as the resultant dipole moment of the N−H bonds. In NF3, the orbital dipole is in the opposite direction to the resultant dipole moment of the N−F bonds. Thus, dipole moment of NH3 (1.47 D) is higher than NF3 (0.23 D). Statement A is incorrect.
Statement B: BeH2 is a linear molecule (sp hybridization). The two Be−H bond dipoles are equal and opposite, so they cancel each other out, making the net dipole moment zero. Statement B is correct.
Statement C: O22− has 18 electrons. Its bond order is 210−8=1. F2 also has 18 electrons and its bond order is 1. Statement C is correct.
Statement D: In the Lewis structure of ozone (O3), the central oxygen atom forms one double bond and one single bond and has one lone pair. Formal charge = V−L−2B=6−2−26=+1. Statement D is incorrect.
Statement E: NO2 is an odd-electron molecule (17 valence electrons). The nitrogen atom has only 7 electrons in its valence shell, so it does not satisfy the octet rule. Statement E is incorrect.
Therefore, only statements B and C are correct.