Flux is used to remove ...... .

In the wrought iron of the iron pillar located in Delhi,what other elements are present besides iron?

Given below are two statements:
Statement $I$: During electrolytic refining,the pure metal is made to act as anode and its impure metallic form is used as cathode.
Statement $II$: During the Hall-Heroult electrolysis process,purified $Al_2O_3$ is mixed with $Na_3AlF_6$ to lower the melting point of the mixture.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which one of the following statements is incorrect?

Which of the following changes involve more than two metallurgical processes?

Which of the following is an incorrect match?