ICSE Class 10 Answered

Metals of low reactivity cannot displace high reactive metals from their salts. Also, it has affinity for oxygen. For this reason oxides of aluminium cannot be reduced easily either by carbon, hydrogen or carbon monoxide.

Zinc oxide can be reduced to zinc by using carbon monoxide because oxides of zinc is placed below aluminium and can be reduced on heating with carbon, carbon monoxide and hydrogen. Zinc is mostly available in its carbonates and sulphides. So this metal carbonates and metal sulphides initially get converted into oxide form. Hence Zinc oxide reduced using common reducing agents like carbon, carbon monoxide and hydrogen.