Factors Affecting the Rate of Reaction

Factors Affecting the Rate of Reaction MDCAT MCQs with answers

12 past paper MCQs on Factors Affecting the Rate of Reaction, from the Reaction Kinetics unit of MDCAT Chemistry. The year each question appeared is shown where known; tap “Show answer” for the correct option and a short solution.

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1.In a reversible reaction, a catalyst lowers the activation energy of the: (MDCAT 2020)

  1. forward reaction
  2. reverse reaction
  3. forward as well as the reverse reaction
  4. forward reaction but raises that of the reverse reaction
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Correct answer: (c) forward as well as the reverse reaction

The catalyst offers a lower path between the same two states, so both directions are speeded up equally and the equilibrium is unmoved.

2.A catalyst which is in the same phase as the reactants is known as: (MDCAT 2022)

  1. a heterogeneous catalyst
  2. a homogeneous catalyst
  3. a slow catalyst
  4. a fast catalyst
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Correct answer: (b) a homogeneous catalyst

One phase throughout is what homogeneous means.

3.The rate of a chemical reaction changes with: (KMU MDCAT 2025)

  1. Concentration of reactant molecules
  2. Concentration of product molecules
  3. Concentration of both reactant and product
  4. Rate constant
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Correct answer: (a) Concentration of reactant molecules

The rate law is written in the concentrations of the reactants alone.

4.Orientation of molecule is more important in following cases except: (SZABMU MDCAT 2025)

  1. High Pressure
  2. complex molecules
  3. poly atomic molecules
  4. low pressure
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Correct answer: (d) low pressure

At low pressure the molecules are far apart and collisions are rare, so how they are turned matters least.

5.Formation of hydrogen gas can be increased by reacting which Zn sample with 1M HCl? (NUMS MDCAT 2024)

  1. 1g Zn Rod
  2. 1g Zn Pellets
  3. 1g Zn Ribbon
  4. 1g Zn Powder
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Correct answer: (d) 1g Zn Powder

The powder offers by far the greatest surface for the acid to attack.

6.Q.87 The catalysis in which the catalyst and the reactants are in the same phase is known? (UHS MDCAT 2023)

  1. Heterogeneous catalyst
  2. Homogeneous catalyst
  3. Slow
  4. Fast
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Correct answer: (b) Homogeneous catalyst

A catalyst in the same phase as the reactants is a homogeneous catalyst.

7.When temperature of reacting gases is raised by 10 K, the reaction rate will increase to: (NUMS MDCAT 2023)

  1. Double
  2. Three times
  3. Four times
  4. Five times
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Correct answer: (a) Double

As a rough rule the rate doubles for every ten kelvin rise.

8.Number of molecules possessing Ea (Activation Energy) can be increased by (PMC MDCAT 2022)

  1. Adding a catalyst
  2. increasing the volume
  3. increasing temperature
  4. increasing temperature of Moles of Reactants
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Correct answer: (c) increasing temperature

Heating spreads the energies upwards, so a far larger fraction of molecules clears the barrier.

9.The slowest reaction among these is (PMC MDCAT 2022)

  1. Neutralization
  2. Double Decomposition Reactions
  3. Ionic Reactions
  4. Hydrogenation Reaction
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Correct answer: (d) Hydrogenation Reaction

Hydrogenation needs bonds broken and a catalyst; ionic reactions need only a meeting of ions.

10.Rate of any reaction depends upon: (NUMS MDCAT 2022)

  1. Temperature
  2. Concentration
  3. Pressure
  4. Rate constant
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Correct answer: (a) Temperature

Raising the temperature speeds almost every reaction, and steeply.

11.What is "NOT TRUE" about rate of a reaction? (NUMS MDCAT 2022)

  1. Concentration of reactants does not affect the rate of a reaction
  2. Surface area of reactants affects rate of reaction
  3. Concentration affects rate of reaction
  4. Catalyst affects rate of a reaction
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Correct answer: (a) Concentration of reactants does not affect the rate of a reaction

Concentration does affect the rate; that is what the rate law says.

12.Role of a catalyst in a chemical reaction is to: (UHS MDCAT 2018)

  1. Decreases yield of a reaction
  2. Decreases rate of a reaction
  3. Increase yield of product
  4. Increase rate of a reaction
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Correct answer: (d) Increase rate of a reaction

A catalyst offers a path of lower activation energy; it does not change the yield.

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