Question

Choose the incorrect statement from the following:

• A. Isoletronic molecules/ions have the same bond order.
• B. Dipole moment of \(NH_3\) is greater than that of \(NF_3\).
• C. The Carbon in Methyl Carbocation is \(sp^3\) hybridised.
• D. The stability of an ionic compound is measured in terms of its lattice enthalpy and not simply based on attaining Octet configuration.

Hint:

In ionic compounds, lattice enthalpy is the dominant factor in stability, not just the attainment of octet configuration. Also, isoelectronic molecules do not always share the same bond order.

Answer 1

The Correct Option is A

- Statement A is incorrect. Isoletronic molecules/ions have the same number of electrons, but they do not necessarily have the same bond order. Bond order depends on the molecule's structure and the type of bonding involved, not just on the number of electrons.
- Statement B is correct. The dipole moment of \(NH_3\) is indeed greater than that of \(NF_3\) because in \(NH_3\), the nitrogen atom has a greater tendency to pull electron density from the hydrogen atoms due to the smaller atomic size and the lone pair on nitrogen.
- Statement C is correct. The carbon in methyl carbocation (\(CH_3^+\)) is indeed \(sp^2\) hybridised, not \(sp^3\). The carbon atom in a carbocation has an empty \(p\)-orbital that participates in bonding, leading to \(sp^2\) hybridisation.
- Statement D is correct. The stability of an ionic compound is primarily determined by its lattice enthalpy, which is a measure of the strength of the ionic bond formed between oppositely charged ions. This is more significant than the mere attainment of an octet.