Here below some basic MCQ’s about “Rate of Reaction” with answer which is well explained. Let’s check one by one which is given below.
MCQ 1:
Which of the following factors does NOT affect the rate of a chemical reaction?
A) Concentration of reactants
B) Temperature
C) Presence of a catalyst
D) Color of the reactants
Answer: D) Color of the reactants
Explanation: The rate of a chemical reaction is influenced by factors such as the concentration of reactants, temperature, and the presence of a catalyst. The color of the reactants does not impact the rate of the reaction.
MCQ 2:
What effect does increasing the temperature have on the rate of a chemical reaction?
A) Decreases the rate
B) Increases the rate
C) No effect
D) Stops the reaction
Answer: B) Increases the rate
Explanation: Increasing the temperature typically increases the kinetic energy of the molecules involved in the reaction, leading to more frequent and energetic collisions. This generally results in an increased rate of reaction.
MCQ 3:
In a chemical reaction, what is the role of a catalyst?
A) It increases the temperature of the reaction.
B) It provides energy for the reaction.
C) It lowers the activation energy required for the reaction.
D) It is consumed in the reaction.
Answer: C) It lowers the activation energy required for the reaction.
Explanation: A catalyst is a substance that increases the rate of a reaction by lowering the activation energy without being consumed in the process. This allows more reactant molecules to have sufficient energy to react.
MCQ 4:
Which of the following statements is true regarding the rate of reaction?
A) The rate of reaction is constant throughout the reaction.
B) The rate of reaction decreases as the reaction progresses.
C) The rate of reaction can only be increased by adding more reactants.
D) The rate of reaction is independent of the nature of reactants.
Answer: B) The rate of reaction decreases as the reaction progresses.
Explanation: In most chemical reactions, the rate decreases over time as the reactants are consumed. As the concentration of reactants decreases, the frequency of effective collisions also decreases, leading to a slower rate of reaction.
MCQ 5:
Which of the following is an example of a homogeneous catalyst?
A) Platinum in catalytic converters
B) Enzymes in biological reactions
C) Iron filings in the Haber process
D) Calcium carbonate in acid reaction
Answer: B) Enzymes in biological reactions
Explanation: Enzymes are biological catalysts that operate in the same phase as the reactants (usually in solution), making them homogeneous catalysts. The other options involve catalysts that are not in the same phase as the reactants.
MCQ 6:
Which of the following describes the relationship between the concentration of reactants and the rate of reaction?
A) Directly proportional
B) Inversely proportional
C) Exponential
D) No relation
Answer: A) Directly proportional
Explanation: In many reactions, an increase in the concentration of reactants leads to an increase in the rate of reaction, as there are more molecules available to collide and react.
MCQ 7:
What is the effect of increasing surface area on the rate of reaction?
A) Decreases the rate
B) Increases the rate
C) No effect
D) Stops the reaction
Answer: B) Increases the rate
Explanation: Increasing the surface area of solid reactants allows for more collisions between reactant particles, which typically results in a faster reaction rate.
MCQ 8:
Which type of reaction typically has a high activation energy?
A) Combustion reactions
B) Photochemical reactions
C) Enzymatic reactions
D) Synthesis reactions
Answer: B) Photochemical reactions
Explanation: Photochemical reactions, which require energy from light to proceed, often have higher activation energies compared to other types of reactions.
MCQ 9:
What does the term “activation energy” refer to?
A) The energy required to initiate a reaction
B) The energy released during a reaction
C) The energy needed to break chemical bonds
D) The energy of the products
Answer: A) The energy required to initiate a reaction
Explanation: Activation energy is the minimum energy that reacting species must possess in order to undergo a chemical reaction.
MCQ 10:
In a reaction where the rate doubles when the concentration of a reactant is doubled, the reaction is said to be:
A) First-order
B) Second-order
C) Zero-order
D) Third-order
Answer: A) First-order
Explanation: A first-order reaction shows a linear relationship between the concentration of a reactant and the rate of reaction; doubling the concentration doubles the rate.
MCQ 11:
Which of the following factors can change the equilibrium constant of a reaction?
A) Concentration of reactants
B) Temperature
C) Pressure
D) Catalyst
Answer: B) Temperature
Explanation: The equilibrium constant for a reaction is affected by temperature changes. The concentrations of reactants and products at equilibrium do not change the value of the equilibrium constant.
MCQ 12:
Which of the following statements about a catalyst is FALSE?
A) Catalysts are consumed in the reaction.
B) Catalysts lower activation energy.
C) Catalysts can be recovered unchanged after the reaction.
D) Catalysts speed up the rate of reaction.
Answer: A) Catalysts are consumed in the reaction.
Explanation: Catalysts are not consumed during the reaction; they remain unchanged and can be reused.
MCQ 13:
What type of reaction is characterized by the formation of an intermediate species?
A) Combustion
B) Chain reaction
C) Reversible reaction
D) Photochemical reaction
Answer: B) Chain reaction
Explanation: In a chain reaction, reactive intermediates are formed and consumed in a cyclic manner, often leading to rapid propagation of the reaction.
MCQ 14:
For a reaction to occur, what must happen between reactant molecules?
A) They must collide.
B) They must be at high pressure.
C) They must be in the same phase.
D) They must absorb heat.
Answer: A) They must collide.
Explanation: For a reaction to occur, reactant molecules must collide with sufficient energy and proper orientation to break bonds and form new products.
MCQ 15:
In a zero-order reaction, the rate of reaction:
A) Increases with increasing concentration of reactants.
B) Is constant and independent of reactant concentration.
C) Decreases as reactants are consumed.
D) Is proportional to the square of the concentration of reactants.
Answer: B) Is constant and independent of reactant concentration.
Explanation: In a zero-order reaction, the rate is constant and does not depend on the concentration of the reactants.
MCQ 16:
Which of the following will likely increase the rate of a reaction involving gases?
A) Decreasing the volume of the reaction vessel
B) Increasing the temperature
C) Increasing the concentration of the reactants
D) All of the above
Answer: D) All of the above
Explanation: All these factors—decreasing the volume (which increases pressure), increasing temperature, and increasing concentration—will generally increase the rate of reaction for gaseous reactants.
MCQ 17:
Which of the following is an example of a heterogeneous catalyst?
A) Platinum in catalytic converters
B) Enzymes
C) Iron in the Haber process
D) Sodium hydroxide in acid-base reactions
Answer: C) Iron in the Haber process
Explanation: Iron acts as a solid catalyst in the Haber process for ammonia synthesis, making it a heterogeneous catalyst, as it is in a different phase than the gaseous reactants.
MCQ 18:
The rate of a chemical reaction is typically measured in terms of:
A) Volume of reactants consumed
B) Mass of products formed per unit time
C) Change in concentration of reactants or products per unit time
D) Temperature change
Answer: C) Change in concentration of reactants or products per unit time
Explanation: The rate of reaction is defined as the change in concentration of a reactant or product over a specific time interval.
MCQ 19:
A reaction is described as being “first order” with respect to a particular reactant if:
A) The rate of reaction is independent of the concentration of that reactant.
B) The rate of reaction is proportional to the square of the concentration of that reactant.
C) The rate of reaction is directly proportional to the concentration of that reactant.
D) The reaction does not occur.
Answer: C) The rate of reaction is directly proportional to the concentration of that reactant.
Explanation: A first-order reaction shows a linear relationship where the rate increases proportionally with the concentration of that reactant.
MCQ 20:
What happens to the rate of a reaction when a reactant is in excess?
A) The rate decreases.
B) The rate remains unchanged.
C) The rate increases significantly.
D) The reaction stops.
Answer: B) The rate remains unchanged.
Explanation: If one reactant is in excess, the rate of the reaction is primarily dependent on the concentration of the limiting reactant, so the rate remains unchanged until that reactant is consumed.
Leave a comment