Given below are statements about some molecules/ions. Identify the...

Statement A: In $NH_3$, the orbital dipole due to the lone pair is in the same direction as the resultant dipole moment of the $N-H$ bonds. In $NF_3$, the orbital dipole is in the opposite direction to the resultant dipole moment of the $N-F$ bonds. Thus, dipole moment of $NH_3$ ($1.47\ D$) is higher than $NF_3$ ($0.23\ D$). Statement A is incorrect.
Statement B: $BeH_2$ 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: $O_2^{2-}$ has 18 electrons. Its bond order is $\frac{10-8}{2} = 1$. $F_2$ also has 18 electrons and its bond order is 1. Statement C is correct.
Statement D: In the Lewis structure of ozone ($O_3$), the central oxygen atom forms one double bond and one single bond and has one lone pair. Formal charge = $V - L - \frac{B}{2} = 6 - 2 - \frac{6}{2} = +1$. Statement D is incorrect.
Statement E: $NO_2$ 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.