Decomposition Reaction MCQs

A decomposition reaction involves the breakdown of a compound into two or more of its simpler constituents. Typically, this reaction is represented as AB → A + B. However, not all decomposition reactions are redox reactions. Synthesis is the reverse process, where a new compound forms from the combination of two or more reactants. Decomposition reactions require energy—such as heat, electricity, or light—to break the chemical bonds. They can be categorized into thermal, electrolytic, and photolytic decomposition reactions.

Decomposition of hydrogen peroxide to give H2O + O2 is an example of

(a) reduction
(b) oxidation
(c) both (a) and (b)
(d) none of the above

The correct expression for decomposition of silver chloride to silver and chlorine is

(a) AgCl_2(s)→ Ag_(s)+2Cl_(g)
(b) 2AgCl_(s)→ 2Ag_(s)+ Cl_2(g)
(c) AgCl_2(s)→ Ag_(s)+Cl_2(g)
(d) AgCl_(s)→ Ag_(s)+Cl_(g)

CO2 obtained by the complete decomposition of 20 g CaCO₃ at STP is

(a) 4.48 l
(b) 2.24 l
(c) 44.8 l
(d) 48.4 l

The reaction 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂ is a type of _______reaction.

(a) displacement
(b) double decomposition
(c) decomposition
(d) none of the above

A reaction where two compounds exchange their atoms to form new compounds

(a) decomposition
(b) double displacement
(c) displacement
(d) synthesis

On passing current through acidified water, we get hydrogen and oxygen. This is a type of

(a) oxidation reaction
(b) thermal decomposition
(c) electrolysis
(d) none of the above

The decomposition of silver chloride occurs by

(a) heat
(b) sunlight
(c) water
(d) electricity

Find out the volume of CO2 liberated after heating 9.85 g of BaCO3 at STP.

(a) 2.06 l
(b) 2.12 l
(c) 1.12 l
(d) 4.84 l

Ferrous sulphate on heating gives a reddish-brown residue of ferric oxide. This is due to

(a) decomposition
(b) displacement
(c) combination
(d) none of the above

How many moles of sodium carbonate are formed on decomposition of 0.2 moles of sodium bicarbonate?

(a) 0.1
(b) 0.2
(c) 0.05
(d) 0.025