The correct option(s) related to the extraction of iron from its...

(A) Limestone is added to remove silica as impurity.

$CaO + {SiO}_{2} \to {CaSiO}_{3} ( inthetemperaturerange900 – 1500K )$

(B) Pig iron obtained from blast furnace contains $4$ carbon and many other impurities (eg. $S, P, Si, Mn$) in small amount.

In fusion zone molten iron becomes heavy by absorbing elemental impurities and produces Pig iron. (in the temperature range 900 – 1500 K)

(C) Coke $\left(C\right)$ converts ${CO}_{2} in CO$.

$C + {CO}_{2} \to 2CO$

(D) Exhaust gases consist of $CO and {CO}_{2}$.

Exhaust gases does not contain NO₂

Hence, (A,B,C) are correct.