JEE Main 201911 JanuaryEvening Shift

JEE Main 2019 · 11 January · Evening Shift · Chemistry · General Principles and Processes of Isolation of Metals

The reaction that does NOT define calcination is:

Options

A $\mathrm{Fe}_{2} \mathrm{O}_{3} \cdot \mathrm{xH}_{2} \mathrm{O} \stackrel{\Delta}{\longrightarrow} \mathrm{Fe}_{2} \mathrm{O}_{3}+\mathrm{xH}_{2} \mathrm{O}$
B $2 \mathrm{Cu}_{2} \mathrm{~S}+3 \mathrm{O}_{2} \stackrel{\Delta}{\longrightarrow} 2 \mathrm{Cu}_{2} \mathrm{O}+2 \mathrm{SO}_{2}$
C $\mathrm{ZnCO}_{3} \stackrel{\Delta}{\longrightarrow} \mathrm{ZnO}+\mathrm{CO}_{2}$
D $\mathrm{CaCO}_{3} \cdot \mathrm{MgCO}_{3} \stackrel{\Delta}{\longrightarrow} \mathrm{CaO}+\mathrm{MgO}+2 \mathrm{CO}_{2}$

B. $2 \mathrm{Cu}_{2} \mathrm{~S}+3 \mathrm{O}_{2} \stackrel{\Delta}{\longrightarrow} 2 \mathrm{Cu}_{2} \mathrm{O}+2 \mathrm{SO}_{2}$

Calcination involves heating of carbonates or hydrated oxides in absence of air. \therefore 2

\mathrm{Cu}_{2} \mathrm{~S}+

\mathrm{O}_{2} \stackrel{\Delta}{\longrightarrow}

\mathrm{Cu}_{2} \mathrm{O}+

\mathrm{SO}_{2}

;

\text{ is roasting } (

heating in a regular supply of air).