Question

Which of the following equations are examples of roasting of the respective metal ore?
(i) ${\text{CaCO}}_3\text{(s)}$ $\to$ $\text{CaO (s)}+{\text{CO}}_2\text{(g)}$
(ii) $2{\text{Al(OH)}}_3\text{(s)}$ $\to$ ${\text{Al}}_2{\text{O}}_3\text{(s)}$ + ${\text{3H}}_2\text{O (l)}$
(iii) $2\text{CuS(s)}$+ $2{\text{O}}_2\text{(g)}$ $\to$ $2\text{Cu(s)}$ + ${\text{2SO}}_2\text{(g)}$

• A. Only (ii)
• B. (i) , (ii) and (iii)
• C. (i) and (ii)
• D. Only (iii)

Answer 1

The correct option is D Only (iii)

Roasting is a process in which an ore is heated in the presence or excess of oxygen to convert it into metal oxide. Roasting is generally used for conversion of sulphide ores. So, the chemical reaction (iii) is example of roasting. The correct answer is (c).

Other two given reactions take place in absence of oxygen and are examples of calcination.