1.

Two ores A and B were taken. On heating, ore A gives `CO_(2)` whereas, ore B gives `SO_(2)`. What steps will you take to convert them into metals ?

Answer» Since ore A gives `CO_(2)` on heating, it must be a carbonate of moderately reactive reative metal like Zn. Hence, it willl be first subjected to calcination (to canvert carbonate ore into metal oxide) followed by reduction ( to convert metal oxide to metal).
e.g., `ZnCO_(3)` (calamine).
`ZnCO_(3)overset("Heat")toZnO+CO_(2)" (calcination)"`
To convert it into metal treat it with carbon.
`Zn+C toZn+CO`
Since, B gives `SO_(2),` B must be a sulphide ore, e.g., `Cu_(2)S,HgS,` etc. Hence it will be first subjected to roasting (to convert metal oxide to metal).
`2ZnS+3O_(2)overset(800^(@)C)to2ZnO+2SO_(2)" (roasting)"`
`2Cu_(2)S+3O_(2)overset(Delta)to2Cu_(2)O+2SO_(2)`
`2HgS+3O_(2)overset(Delta)to2HgO+2SO_(2)`
From these oxide metal is obtained either by using reducing agent like C or by autoreduction.
`ZnO+CtoZn+CO`
`Cu_(2)S+2Cu_(2)Oto6Cu+SO_(2)`


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