The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is : (Atomic mass Al = 27)A)180 kgB)270 kgC)540 kgD)90 kg

Also explain.

Bauxite is not directly used in Hall's process. It is first converted into alumina by Bayer's process.
Reaction of carbon with Al₂O₃ forming Aluminium and carbon dioxide is given :
2Al₂O₃ + 3C  $\to$4Al  + 3CO₂

​Molar mass of Al = 27 g mol^-1​
​Molar mass of Al₂O₃ = 118 g mol^-1
​Molar mass of Carbon = 12 g mol^-1

Thus, we can see that according to this reaction, (4$\times$27) = 108 g of Al is formed from the reduction of Al₂O₃ by (3$\times$12) = 36 g of carbon.
108 g of Al produced by 36 g of Carbon
27000 g of Al is formed by (36 / 108) $\times$27000
= 90000 g or 90 kg (aaprox.)