Free Activation Energy and Activated Complex MCQs with Answers
20 Activation Energy and Activated Complex MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Activation energy is the minimum energy reactant particles need to form the activated complex, or transition state, during a reaction. Energy profile diagrams show the forward and reverse activation energies, while catalysts provide an alternative pathway with lower activation energy without changing the reaction enthalpy.
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20 questions
- A. melt the reactants
- B. break all the bonds in the products
- C. form the activated complex from the reactants
- D. keep the products stable
Explanation: Reactant molecules must climb an energy barrier to reach the transient, unstable arrangement called the activated complex or transition…
Correct answer: form the activated complex from the reactants- A. a stable intermediate that can be isolated
- B. the same as the catalyst
- C. the product of the reaction
- D. a short lived arrangement at the top of the energy barrier in which bonds are partly broken and partly formed
Explanation: At the transition state old bonds are stretched and new ones are only beginning to form, so the species exists for the duration of a…
Correct answer: a short lived arrangement at the top of the energy barrier in which bonds are partly broken and partly formed- A. the products lie at a lower energy level than the reactants
- B. the products lie above the reactants
- C. there is no activation energy barrier
- D. the activation energy is always zero
Explanation: An exothermic reaction releases energy to the surroundings, so the products sit lower and the enthalpy change is negative, but the curve…
Correct answer: the products lie at a lower energy level than the reactants- A. Bond energy
- B. Activation energy
- C. Average energy
- D. Enthalpy
Explanation: Activation energy is the barrier reactant molecules must climb to reach the transition state, and only collisions carrying at least this…
Correct answer: Activation energy- A. Ea
- B. P.E
- C. V
- D. K.E
Explanation: Activation energy, Ea, is the minimum energy required for reactants to reach the transition state or activated complex.
Correct answer: Ea- A. Pressure
- B. Effective collision
- C. Ineffective collisions
- D. Temperature
Explanation: An activated complex forms when reactant particles undergo an effective collision with suitable energy and orientation, allowing them to…
Correct answer: Effective collision- A. Increases the rate of forward reaction only
- B. Increases the rate of reverse reaction
- C. Increases the rate of forward but decreases the rate of backward reaction
- D. Increases the rate of forward as well as backward reaction equally
Explanation: A catalyst provides an alternative pathway with lower activation energy for both the forward and reverse reactions.
Correct answer: Increases the rate of forward as well as backward reaction equally8. Anything which increases rate of reaction without being involved in the reaction________________?
- A. Promoter
- B. Catalyst
- C. Inhibitor
- D. All of the above
Explanation: A catalyst increases reaction rate by providing an alternative pathway with lower activation energy and is regenerated by the end of the…
Correct answer: Catalyst- A. Average Kinetic Energy of the molecules
- B. Potential Energy of the molecules
- C. Free Energy of the molecules
- D. Activation Energy of the molecules
Explanation: Activation energy is the minimum energy that the reactants must have to be converted into products.
Correct answer: Activation Energy of the molecules- A. Cannot be Separated from reaction mixture
- B. Contain normal bonds
- C. Can be isolated from a reaction mixture
- D. Both B and C
Explanation: A reaction intermediate cannot be separated from the reaction mixture, as it is usually present only transiently during a…
Correct answer: Both B and C- A. Lower the activation energy
- B. Increase the activation energy
- C. Lower the pH
- D. Decrease the temp of the reaction
Explanation: A catalyst reduces the activation energy of a chemical reaction by providing an alternate route.
Correct answer: Lower the activation energy- A. Pressure
- B. Concentration of a substance
- C. Volume
- D. Temperature
Explanation: Arrhenius' equation in thermodynamics is:k = Ae-Ea/RT wherek = rate constantA = pre-exponential factorEa = activation energyR = universal…
Correct answer: Temperature- A. Highly stable
- B. Moderate stable
- C. Highly unstable
- D. In the low energy state
Explanation: The transition state (or activated complex) occurs at the maximum of the potential energy diagram along the reaction coordinate.It is a…
Correct answer: Highly unstable- A. The enthalpy
- B. The entropy
- C. The activation energy
- D. The free energy
Explanation: A catalyst provides an alternative reaction pathway with lower activation energy.This increases the reaction rate without affecting ΔH…
Correct answer: The activation energy- A. Increasing the reaction temperature.
- B. Increasing the concentration of reactants.
- C. Providing an alternative reaction pathway with a lower activation energy.
- D. Shifting the equilibrium towards the products.
Explanation: A catalyst speeds up a reaction without being consumed by providing a different mechanism or pathway for the reaction to follow.
Correct answer: Providing an alternative reaction pathway with a lower activation energy.- A. A catalyst changes the potential energies of the reactants and products
- B. A catalyst decreases the temperature of the reaction which leads to a faster rate
- C. A catalyst lowers the activation energy barrier for the reaction by providing a different reaction mechanism.
- D. A catalyst raises the activation energy for the reaction which produces a faster rate
Explanation: Catalysts function by providing an alternate reaction mechanism that has a lower activation energy.Note that a catalyst decreases the…
Correct answer: A catalyst lowers the activation energy barrier for the reaction by providing a different reaction mechanism.17. The minimum amount of energy required by the colliding particles for effective collisions is called:
- A. Activation energy
- B. Lattice energy
- C. Bond energy
- D. Hydration energy
Explanation: Explanation for this question will be added soon.
Correct answer: Activation energy- A. More Energy
- B. No energy
- C. Less Energy
- D. A catalyst
Explanation: Exothermic reactions are bond-making reactions in which heat energy is released.
Correct answer: Less Energy- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The activation energy is the lowest in Option C, hence it would be the most rapid reaction among the other options.
Correct answer: Option C- A. Forward activation energy < reverse activation energy
- B. Forward activation energy = reverse activation energy
- C. Forward activation energy > reverse activation energy
- D. No change
Explanation: In an endothermic reaction, the forward reaction generally requires more energy than the reverse reaction.
Correct answer: Forward activation energy > reverse activation energyActivation Energy and Activated Complex MCQs: common questions
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