Cellulose upon acetylation with excess acetic anhydride/H$$_2$$SO$$_4$$ (catalytic) gives cellulose triacetate whose structure is :

In the following reaction sequence, the correct structure of E, F and G are :

Among the following, the coloured compound is :

Both [Ni(CO)$$_4$$] and [Ni(CN)$$_4$$]$$^{2-}$$ are diamagnetic. They hybridisations of nickel in these complexes, respectively, are :