Chemistry - Metallurgy Question with Solution | TestHub

(A) Correct: Roasting temperature ($T_2$) is kept below the melting points of PbS and PbO to prevent them from fusing into a mass that stops the reaction.

(B) Correct: Sulfide roasting is inherently an exothermic oxidation process that releases significant heat.

(C) Correct: This is a self-reduction redox reaction where S²⁻ reduces Pb²⁺ to metallic lead (Pb⁰) while being oxidized to SO₂.

(D) Correct: Extracting lead in liquid (molten) form increases the system's entropy ($\Delta S$), which makes Gibbs free energy ($\Delta G=\Delta H-T\Delta S$) more negative and more thermodynamically favorable.