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

In the electrolysis of $Al_2O_3$ by the Hall-Heroult process,which of the following statements is correct?

For the following statements,mark $T$ for true and $F$ for false statement.
Statement $1$: $SnO_2 +$ wolframite,in this $SnO_2$ is magnetic while wolframite is non-magnetic in nature.
Statement $2$: Argentite ore is concentrated by froth floatation method.
Statement $3$: Copper and lead ores are reduced by self-reduction method.
Statement $4$: In metallurgy of $Fe$,$CO$ is used as a reducing agent at low temperature.

Which of the following elements constitutes a major impurity in pig iron?

Which of the following statements is correct?

The major components of German Silver are: