Dynamic Equilibrium in Reversible Reactions

Steps:

• Recognize the decomposition of calcium carbonate as a reversible reaction: CaCO₃ ⇌ CaO + CO₂.
• Note the closed container traps CO₂, allowing the reverse reaction to occur.
• Identify that equal decomposition and recombination rates mean no net change in concentrations.
• Conclude this state is dynamic equilibrium, where both reactions continue at matching speeds.

Why C is correct:

• Equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products.

Why the others are wrong:

• A: Activation energy is the minimum energy required to start a reaction, not a state of balanced rates.
• B: Backward reaction describes the reverse process alone, not the balanced condition.
• D: Neutralisation is the reaction between an acid and base to form salt and water, unrelated to decomposition.

Final answer: C