Extraction of Metals - Result Question 10
####10. The pair that does not require calcination is
(2019 Main, 12 Jan II)
(a) $ZnO$ and $MgO$
(b) $ZnO$ and $Fe _2 O _3 \cdot x H _2 O$
(c) $ZnCO _3$ and $CaO$
(d) $Fe _2 O _3$ and $CaCO _3 \cdot MgCO _3$
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Solution:
- The hydroxide, hydrated oxides and carbonate ores, after concentration, are subjected to calcination. In the process, the ore is heated below its melting point in the limited supply or absence of air. As the result, these are converted into their oxides.
So, among the given options, the options having either carbonates (e.g. $ZnCO _3$ and $CaCO _3 \cdot MgCO _3$ ) or hydrated oxide (e.g. $Fe _2 O _3 \cdot x H _2 O$ ), require calcination while pair of option (a), i.e. $ZnO$ and $MgO$ does not require calcination.
