Question

The gases involved in the decomposition of lead nitrate are:
A. ${{\rm{N}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}},{\rm{NO}}$
B. ${\rm{N}}{{\rm{O}}_2},{{\rm{O}}_2}$
C. ${{\rm{N}}_{\rm{2}}}{{\rm{O}}_{\rm{3}}},{{\rm{O}}_2}$
D. ${{\rm{N}}_{\rm{2}}}{\rm{O}},{{\rm{O}}_2}$

Answer 1

Hint: We know that there are four types of reaction. Decomposition reaction is one of them. In this reaction a substance breaks to form two or more compounds.

Complete answer:
Lead (II) nitrate is an inorganic compound having molecular formula ${\rm{Pb}}{\left( {{\rm{N}}{{\rm{O}}_{\rm{3}}}} \right)_2}$ . It is also known as plumbous nitrate. It exists mainly in colourless crystalline forms and soluble in water. It is toxic in nature and hence, to be handled with care to prevent ingestion, inhalation and skin contact.
The heating of lead (II) nitrate gives lead (II) oxide, nitrogen dioxide and oxygen. The balanced chemical reaction for the decomposition of lead (II) nitrate can be shown as below.

${\rm{2Pb}}{\left( {{\rm{NO}}} \right)_{\rm{3}}}\left( s \right) \to 2{\rm{PbO}}\left( s \right) + 4{\rm{N}}{{\rm{O}}_{\rm{2}}}\left( g \right) + {{\rm{O}}_{\rm{2}}}\left( g \right)$

From the above decomposition reaction of lead nitrate, we find that two gases are released in the reaction. The names of the gases are nitrogen dioxide and oxygen gas.

Hence, the correct option is B, that is, ${\rm{N}}{{\rm{O}}_2},{{\rm{O}}_2}$.

Additional Information:
The other three types of reactions are combination reaction, displacement reaction and double displacement reaction.
> Combination reaction is the reaction in which two or more reactants combine to form a product.
One example of combination reaction is formation of water from oxygen and hydrogen.

${\rm{2}}{{\rm{H}}_{\rm{2}}} + 2{{\rm{O}}_{\rm{2}}} \to 2{{\rm{H}}_{\rm{2}}}{\rm{O}}$

> In a displacement reaction, displacement of a less reactive metal from its compound by a highly reactive metal takes place.

${\rm{Fe}} + {\rm{CuS}}{{\rm{O}}_{\rm{4}}} \to {\rm{Cu}} + {\rm{FeS}}{{\rm{O}}_{\rm{4}}}$

> In a double displacement reaction, the exchange of ions of two ionic compounds takes place. The reaction between potassium nitrate and aluminium chloride represents a double displacement reaction.

${\rm{KN}}{{\rm{O}}_{\rm{3}}} + {\rm{AlC}}{{\rm{l}}_{\rm{3}}} \to {\rm{Al}}{\left( {{\rm{N}}{{\rm{O}}_{\rm{3}}}} \right)_3} + {\rm{KCl}}$

Note: Students may get confused about displacement and decomposition reaction. In decomposition reaction, a substance breaks to form two or more compounds and in a displacement reaction, a more reactive metal displaces a less reactive metal from its compound.