The role of cryolite in the metallurgy of aluminium is :

The value of ∆_fG^O for the formation of ${\mathrm{Cr}}_2{\mathrm{O}}_3$ is – 540 kJmol⁻¹and that of Al₂O₃  is – 827 kJ mol⁻¹. The correct statement is-

1. Cr can reduce Al₂O₃ to Al

2. Cr₂O₃ cannot reduce Al₂O₃ to Al

3. Al can reduce ${\mathrm{Cr}}_2{\mathrm{O}}_3$ to Cr

4. Al cannot reduce ${\mathrm{Cr}}_2{\mathrm{O}}_3$ to Cr

The chemical reactions taking place in the extraction of zinc from zinc blende is

1. $2\mathrm{ZnS}+3{\mathrm{O}}_2\to 2\mathrm{ZnO} + 2{\mathrm{SO}}_2$

2. $\mathrm{ZnO} + \mathrm{C}\stackrel{1673 \mathrm{K}}{\to }\mathrm{Zn} + \mathrm{CO}$

3. Both 1 and 2

4. None of the above

The reaction that do not take place in the blast furnace during the extraction of iron is-

1. Fe₂O_3(s) + 3CO_(g) → 2Fe₃O_4(s) + 3CO_2(g)

2. FeO_(s) + CO_(g) → Fe_(s) + CO_2(g)

3. 2 C_(s) + O_2(g) → 2 CO_(g)

4. None of the above