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A sealed flask of reacting gases shows no colour change for an hour. What is actually happening inside?
Aonly the forward reaction still proceeds
Bboth reactions have completely stopped
Cboth reactions continue at equal rates
Dthe concentrations keep changing steadily
Answer & Solution
Correct answer: C. both reactions continue at equal rates
1. Equilibrium is reached when the forward and reverse rates become equal.
2. Equal rates mean the concentrations stop changing, which is what is observed.
3. But neither reaction has stopped — both continue at the molecular level.
4. Product forms exactly as fast as it is consumed, so the system appears still while remaining active.
5. That ongoing activity beneath an unchanging appearance is exactly what dynamic describes.
_Source: NECTA ACSEE 2023 Chemistry 132/1, Question 8: Chemical Equilibrium_
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