JEE Main · 2023 · 15 Apr 2023 · Shift 1 · General Principles and Processes of Isolation of Metals

Which one of the following is not an example of calcination?

(A) $Fe_{2} O_{3} \cdot xH_{2} O Δ Fe_{2} O_{3} + xH_{2} O$
(B) $CaCO_{3} Δ CaO + CO_{2}$
(C) $CaCO_{3} \cdot MgCO_{3} Δ CaO + MgO + 2 CO_{2}$
(D) $2 PbS + 3 O_{2} Δ 2 PbO + 2 SO_{2}$ ✓ Correct

Answer: (D)

Solution

Calcination is the heating of an ore in the absence or a limited supply of air to drive off volatile matter such as water of hydration or carbon dioxide. Dehydration of hydrated ferric oxide to

F e_{2} O_{3}

, decomposition of calcium carbonate to

CaO

and

C O_{2}

, and decomposition of dolomite to

CaO

MgO

and

C O_{2}

all expel such volatiles and are examples of calcination. Heating galena,

2 PbS + 3 O_{2} Δ 2 PbO + 2 S O_{2}

, is carried out in a plentiful supply of air and oxidises the sulphide to the oxide; this is roasting and is therefore not an example of calcination.

JEE Main · 2023 · 15 Apr 2023 · Shift 1 · Single correct option

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JEE Main · 2023 · 15 Apr 2023 · Shift 1 · General Principles and Processes of Isolation of Metals

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