All Free Chemistry MCQs with Answers
Every Chemistry question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
13,720 questions · page 585 of 686
- A. Ultraviolet radiation
- B. Visible radiation
- C. Infrared radiation
- D. All of these
Explanation: Spectrometry is a versatile analytical method that measures the absorption of electromagnetic radiation by reactants and products.
Correct answer: All of these- A. s-1
- B. mol dm-3 s-1
- C. mol dm-3
- D. mol-1 dm3
Explanation: In a first-order reaction, the rate constant k is derived from the formula: k = rate / [A], where [A] is the concentration of a reactant.
Correct answer: s-1- A. Concentration of the reactants becomes irrelevant
- B. Number of efficient or fruit collisions increase
- C. Reaction proceeds without any transition state
- D. Molecules of the reactants move slowly
Explanation: Rate of reaction is directly proportional to no. of effective collision and inversely proportional to activation energy.
Correct answer: Number of efficient or fruit collisions increase- A. Free energy charge
- B. Wander Waal's equation
- C. Arrhenius equation
- D. Kinetic equation
Explanation: Influence of temperature is predicted by Arrhenius equation reactants Rate =temperature Rate = 1 / Ea
Correct answer: Arrhenius equation- A. Increase rate of a reaction
- B. Decrease rate of reaction
- C. Decrease yield of a reactant
- D. Increase yield of product
Explanation: A positive catalyst increase rate of reaction, decreases activation energy, decrease equilibrium time and changes mechanism of reaction.
Correct answer: Increase rate of a reaction- A. The vessel shall be open
- B. Reacting molecules should have less energy than Ea at time of collision
- C. Reacting molecules must be properly oriented and energy more than or equal to Ea
- D. The reacting molecules must not collide with each other
Explanation: The amount of energy required for effective collisions is called activation energy which is required for effective collision along with…
Correct answer: Reacting molecules must be properly oriented and energy more than or equal to Ea- A. Reactant's concentration
- B. Product concentration
- C. Slowest step
- D. All of these
Explanation: The rate of a chemical reaction is primarily dependent on the concentrations of the reactants.
Correct answer: Reactant's concentration11688. Rate of reaction has :
- A. No units
- B. Unit of mol dm-3
- C. Unit as mol dm-3
- D. Unit as mol dm-3s-1
Explanation: The correct answer is D) Unit as mol dm-3 s-1, as it represents the units commonly used to express the rate of reaction.
Correct answer: Unit as mol dm-3s-1- A. Time constant
- B. Relative rate constant
- C. Instantaneous rate constant
- D. Velocity constant
Explanation: The relative rate constant is used when comparing the rates of different reactions, and it can vary from one reaction to another.
Correct answer: Relative rate constant- A. Rising curve
- B. Falling curve
- C. Straight line
- D. None of these
Explanation: During the hydrolysis of an ester, ester bonds are broken down into their respective carboxylic acid and alcohol components.
Correct answer: Rising curve11691. A reaction is first order with respect to A and second order with respect to B, the rate equation is
- A. rate = [A] [B]2
- B. rate = k [A]2[B]
- C. rate = k [A] [B]
- D. rate = k [A]
Explanation: In this option the rate of the reaction is proportional to the product of the concentrations of A and B raised to the power of 2.
Correct answer: rate = [A] [B]211692. A catalyst:
- A. Decreases the activation energy and the rate of reaction
- B. Decreases the activation energy and increases the rate of reaction
- C. Increases the activation energy and decreases the rate of reaction
- D. Increases the activation energy and increases the rate of reaction
Explanation: A catalyst is a substance that lowers the activation energy required for a reaction to occur.
Correct answer: Decreases the activation energy and increases the rate of reaction- A. Concentration
- B. Temperature
- C. Catalyst
- D. Activation energy
Explanation: Option d is correct because activation energy does not directly influence the rate of reaction.
Correct answer: Activation energy11694. If the reaction 'P +Q → R+ S' is described as being of zero order with respect to P, it means that:
- A. P is catalyst in this reaction
- B. P molecules do not possess sufficient energy to react
- C. The concentration of P does not change during the reaction
- D. The rate of reaction is independent of the concentration of P
Explanation: Option d is correct because if a reaction is described as being of zero order with respect to a particular reactant (in this case, P), it…
Correct answer: The rate of reaction is independent of the concentration of P- A. mol dm-3 sec-1
- B. mol-2 dm6
- C. sec-1
- D. mole-1 dm3 sec-1
Explanation: Unit of rate = mol dm-3 sec-1 Unit of a second order reaction is = mol2 dm-6 as the rate eqn:- rate = k[reactants]2 ∴ unit of k = unit of…
Correct answer: mole-1 dm3 sec-1- A. Excludes the average kinetic energy of the reactant
- B. Is in addition to the total K.E. of the reactants
- C. Is in addition to the average K.E. of the products
- D. Is needed for effective collisions
Explanation: Activation energy is needed for effective collision.(BOOK INFORMATION)
Correct answer: Is needed for effective collisions- A. Concentration of reactants decrease
- B. Concentration of product decreases
- C. The order of reaction changes
- D. Temperature of the system changes
Explanation: The reaction rate in forward direction decreases with the passage of time because the concentration of reactants decreases.
Correct answer: Concentration of reactants decrease- A. During a chemical reaction, the particles must collide for a reaction to occur.
- B. Reaction between the colliding particles can only take place if they possess the activation energy upon collision.
- C. Only collisions with the correct spatial orientation are effective in causing a reaction.
- D. All of the above statements are correct.
Explanation: All the given statements are correct assumptions of collision theory.Option A: Acknowledges that collisions are fundamental to initiating…
Correct answer: All of the above statements are correct.- A. The rate of reaction increases with decreasing activation energy.
- B. The rate of reaction is independent of the activation energy.
- C. The rate of reaction decreases with decreasing activation energy.
- D. The rate of reaction increases with increasing activation energy.
Explanation: The rate of a chemical reaction is inversely related to the activation energy.
Correct answer: The rate of reaction increases with decreasing activation energy.- A. These are in pure crystalline state
- B. The activity of enzyme catalyst is inhibited by poison
- C. Enzyme catalytic reactions have maximum rate at optimum temperature
- D. All of these
Explanation: The correct answer is D: All of these. Enzyme catalysts can exist in a pure crystalline state, although this is not a feature of all…
Correct answer: All of these