(N/A) $(i)$ Fractional column: It is a long vertical tube filled with glass beads or metal plates,used in fractional distillation to increase the surface area for heat exchange between rising vapors and falling liquid.
$(ii)$ Theoretical plate: It is a hypothetical zone or stage in a distillation column where two phases (liquid and vapor) establish equilibrium with each other. $A$ higher number of theoretical plates indicates better separation efficiency.
$(iii)$ Mechanism of fractional column: As hot vapors rise through the column,they condense on the cooler surfaces (beads/plates). The heat released by condensation vaporizes the more volatile component from the liquid film. This process repeats multiple times,enriching the vapor in the more volatile component as it moves towards the top.