Which of the following processes is not associated with steel making?

Refer to the periodic table and answer the following questions:
$(a)$ Select the possible non-metals that can show disproportionation reaction.
$(b)$ Select three metals that can show disproportionation reaction.

Which of the following is a disproportionation redox reaction?

$1 \ mole$ of $MnO_4^{2-}$ in neutral aqueous medium disproportionates to:

Disproportionation of $1 \ mol$ of $MnO_4^{2-}$ in neutral aqueous solution results in which of the following?

Which species among the following does not show disproportionation reactions?