Given below are statements about some molecules/ions. Identify the CORRECT statements. A. The dipole moment value of NF₃$\mathrm{NF}_3$ is higher than that of NH₃$\mathrm{NH}_3$. B. The dipole moment value of BeH₂$\mathrm{BeH}_2$ is zero. C. The bond order of O₂²⁻$\mathrm{O}_2^{2-}$ and F₂$\mathrm{F}_2$ is same. D. The formal charge on the central oxygen atom of ozone is -1. E. In NO₂$\mathrm{NO}_2$, all the three atoms satisfy the octet rule, hence it is very stable. Choose the correct answer from the options given below :

Core Logic

(A) Dipole moment of NF₃$\mathrm{NF}_3$ is lower than that of NH₃$\mathrm{NH}_3$ because in NF₃$\mathrm{NF}_3$, the orbital dipole due to the lone pair and the bond dipoles (N-F) are in opposite directions, whereas in NH₃$\mathrm{NH}_3$ they reinforce each other. (Statement A is false).

(B) BeH₂$\mathrm{BeH}_2$ is sp$sp$ hybridized, a linear molecule. The two Be-H bond dipoles cancel out, resulting in a zero net dipole moment. (Statement B is true).

(C) Bond order of O₂²⁻$\mathrm{O}_2^{2-}$ (peroxide ion, 18 e^-$18 e^-$) = 1$= 1$. Bond order of F₂$\mathrm{F}_2$ (18 e^-$18 e^-$) = 1$= 1$. They are isoelectronic and have the same bond order. (Statement C is true).

(D) The formal charge on the central oxygen atom in ozone (O₃$\mathrm{O}_3$) is +1$+1$, not -1$-1$. (Statement D is false).

(E) In NO₂$\mathrm{NO}_2$, nitrogen is an odd-electron species (7+16 = 23 e^-$7+16 = 23 e^-$), thus it does not follow the octet rule. (Statement E is false).

Step 1: Final Conclusion

Only statements B and C are correct.

Pattern Recognition

Ammonia vs Nitrogen trifluoride is a classic NCERT dipole exception. Central atoms with odd electrons (like N in NO$\mathrm{NO}$, NO₂$\mathrm{NO}_2$, ClO₂$\mathrm{ClO}_2$) inherently violate the octet rule.

Chapter Mix

Class 11 Chemistry: Chemical Bonding and Molecular Structure