Choose the incorrect statement from the following: A. Isoelectronic molecules/ions have the same bond order. B. Dipole moment of $\mathrm{NH}_3$ is greater than that of $\mathrm{NF}_3$. C. The Carbon in Methyl Carbocation is $\mathrm{sp}^3$ hybridised. D. The stability of an ionic compound is measured in terms of its lattice enthalpy and not simply based on attaining Octet configuration.

A. Correct: Isoelectronic species like $N_2$, $CO$, $CN^-$, $NO^+$ all have bond order 3 — this holds for many common pairs.

B. Correct: In $NH_3$, N-H bond dipoles and the lone pair dipole reinforce each other. In $NF_3$, the N-F bond dipoles oppose the lone pair dipole, partially canceling it. Hence $\mu(NH_3) > \mu(NF_3)$.

C. Incorrect: The carbon in methyl carbocation ($CH_3^+$) has 3 sigma bonds and one empty p-orbital — it is $sp^2$ hybridised with trigonal planar geometry, not $sp^3$.

D. Correct: The stability of an ionic compound is governed by lattice enthalpy (energy released when gaseous ions form a crystal lattice), not merely by whether the octet rule is satisfied.

The incorrect statement is C.