Given below are two statements related to Ellingham diagram:

Statement I : Ellingham diagrams can be constructed for formation of oxides, sulfides and halides of metals.

Statement II : It consists of plots of $$\Delta_{\mathrm{f}} \mathrm{H}^{0}$$ vs $$\mathrm{T}$$ for formation of oxides of elements.

In the light of the above statements, choose the most appropriate answer from the options given below:

The covalency and oxidation state respectively of boron in $$\left[\mathrm{BF}_{4}\right]^{-}$$, are :

Given below are two statements :

Statement I : Tropolone is an aromatic compound and has $$8 \pi$$ electrons.

Statement II : $$\pi$$ electrons of $$ > \mathrm{C}=\mathrm{O}$$ group in tropolone is involved in aromaticity.

In the light of the above statements, choose the correct answer from the options given below:

Identify the correct order of standard enthalpy of formation of sodium halides :