Question

Metal oxide, sulphur dioxide and oxygen are formed on the decomposition of

• A. Metal carbonates.
• B. Metal sulphates.
• C. Metal nitrates.
• D. Metal chlorates.

Answer 1

The correct option is B

Metal sulphates.

Decomposition reaction: A decomposition reaction is defined as a chemical reaction in which one reactant breaks down into two or more products.

The explanation for the correct answer

Option B

When metal sulphates are heated strongly, they decompose to give their respective oxides, Sulphur dioxide(${\mathrm{SO}}_2$) and Oxygen(${\mathrm{O}}_2$).

Example:

$\underset{\mathrm{Lead}\mathrm{sulphate}}{2{\mathrm{PbSO}}_4(\mathrm{s}})\stackrel{∆}{\to }\underset{\mathrm{Lead}\mathrm{oxide}}{2\mathrm{PbO}\left(\mathrm{s}\right)}+\underset{\mathrm{Sulphur}\mathrm{dioxide}}{2{\mathrm{SO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}$

The explanation for the incorrect answers

Option A

Metal carbonates decompose to form metal oxides and Carbon dioxide gas.

Example

$\underset{\mathrm{Sodium}\mathrm{carbonate}}{{\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)}\stackrel{∆}{\to }\underset{\mathrm{Sodium}\mathrm{oxide}}{{\mathrm{Na}}_2\mathrm{O}\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}$

Option C

Metal nitrate on decomposition forms metal oxide, Nitrogen dioxide, and Oxygen.

Example

$\underset{\mathrm{Magnesium}\mathrm{nitrate}}{2\mathrm{Mg}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right)}\stackrel{∆}{\to }\underset{\mathrm{Magnesium}\mathrm{oxide}}{2\mathrm{MgO}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitrogen}\mathrm{oxide}}{4{\mathrm{NO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}$

Option D

Metal chlorates decompose to form solid metal chlorides and Oxygen gas.

Example

$\underset{\mathrm{Lithium}\mathrm{chlorate}}{2{\mathrm{LiClO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }}\underset{\mathrm{Lithium}\mathrm{chloride}}{2\mathrm{LiCl}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2(\mathrm{g}})$

Conclusion:

Hence option B is correct, when metal sulphates are heated strongly, they decompose to give their respective oxides, sulphur dioxide( ${\mathrm{SO}}_2$) and Oxygen(${\mathrm{O}}_2$).