From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02x10^23 formula units. This implies that 1 mole of MgBr2 also contains 6.02x10^23 formula units.
Now, if 1 mole of MgBr2 contains 6.02x10^23 formula units,
Then Xmol of MgBr2 will contain 6.99x10^20 formula units i.e
The distillation of coal tar can obtain aromatic compounds like benzene and toluene, and also phenolic compounds like phenol. Hence, the only option here that cannot be obtained from the distillation of coal tar is coke.