Get Answers to all your Questions

header-bg qa

The pair that does not require calcination is:

Option: 1

\mathrm{\mathrm{PbO}} and \mathrm{\mathrm{CdO}}

Option: 2

\mathrm{Fe}_2 \mathrm{O}_3 and \mathrm{\mathrm\mathrm{NaHCO}_3}

Option: 3

\mathrm{HgO} and \mathrm{} \mathrm{CaCO}_3

Option: 4

\mathrm{SnO}_2 and \mathrm{ \mathrm{Mg}(\mathrm{OH})_2}

Answers (1)


Calcination refers to the process of heating a substance at high temperatures in order to bring about chemical or physical changes, such as decomposition, oxidation, or removal of volatile components. In the given options, we need to identify the pair that does not require calcination.

\mathrm{PbO} and \mathrm{CdO}: Both \mathrm{PbO} (lead(II) oxide) and \mathrm{CdO} (cadmium(II) oxide) are metal oxides. These oxides can undergo calcination to produce the respective metals (lead and cadmium) or other compounds.

\mathrm{Fe}_2 \mathrm{O}_3 and \mathrm{NaHCO}_3: \mathrm{Fe}_2 \mathrm{O}_3 (iron(III) oxide) is a metal oxide and can undergo calcination to produce iron or other compounds. \mathrm{NaHCO}_3 (sodium bicarbonate) is a compound that can undergo thermal decomposition at high temperatures, resulting in the formation of sodium carbonate, water, and carbon dioxide. Although calcination is not explicitly mentioned for \mathrm{NaHCO}_3 in this option, it does involve heating and decomposition.


\mathrm{HgO} and \mathrm{CaCO}_3 : This is the correct option. \mathrm{HgO} (mercury(II) oxide) and  \mathrm{CaCO}_{3 }  (calcium carbonate) do not require calcination. \mathrm{HgO} can undergo thermal decomposition directly at elevated temperatures, without the need for a separate calcination process, to produce mercury and oxygen.\mathrm{CaCO}_3 can undergo thermal decomposition, known as calcination, to produce calcium oxide (quicklime) and carbon dioxide.

\mathrm{SnO}_2 and \mathrm{Mg}(\mathrm{OH})_2: Both \mathrm{SnO}_2 (tin(IV) oxide) and \mathrm{Mg}(\mathrm{OH})_{2 { }} (magnesium hydroxide) can undergo calcination. \mathrm{SnO}_2 can be calcined to produce tin metal or other compounds.

\mathrm{Mg}(\mathrm{OH})_{2 { }} can be calcined to produce magnesium oxide (\mathrm{MgO}) and water vapor. 

Therefore, the pair that does not require calcination is 3) \mathrm{HgO} and \mathrm{CaCO}_3.

Posted by


View full answer

NEET 2024 Most scoring concepts

    Just Study 32% of the NEET syllabus and Score up to 100% marks