All Free Chemistry MCQs with Answers
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13,720 questions · page 586 of 686
- A. The rate of reaction increases as the reaction proceeds
- B. The rate of reaction decreases as the reaction proceeds
- C. The rate of reaction remains the same as the reaction proceeds
- D. The rate of reaction may decrease or increase as the reaction proceeds
Explanation: The rate of reaction typically decreases as the reaction progresses due to the depletion of reactants and the accumulation of products.
Correct answer: The rate of reaction decreases as the reaction proceeds- A. It does not determines the mechanism of reaction
- B. It is determined experimentally
- C. It is associated with the rate equation
- D. It is always equal to molecularity
Explanation: The statement that the order of a reaction is always equal to its molecularity is incorrect.
Correct answer: It is always equal to molecularity11703. The experimental relationship between rate of reaction and concentration of reactant is called:
- A. Rate Law
- B. Hess's Law
- C. Law of Mass Action
- D. Le Chatelier's Principle
Explanation: The Rate Law is the correct choice because it defines the mathematical relationship between the concentration of reactants and the rate of…
Correct answer: Rate Law- A. A. The oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3) using vanadium(V) oxide (V2O5) as a catalyst.
- B. B. The esterification of acetic acid with ethanol using sulfuric acid (H2SO4) as a catalyst.
- C. C. The decomposition of ozone (O3) using nitric oxide (NO) as a catalyst.
- D. D. The hydrogenation of ethylene (C2H4) using a platinum catalyst.
Explanation: Heterogeneous catalysis occurs when the catalyst and the reactants are in different phases.
Correct answer: A. The oxidation of sulfur dioxide (SO2) to sulfur trioxide (SO3) using vanadium(V) oxide (V2O5) as a catalyst.- A. A. Molecularity of a reaction is always an integer value.
- B. B. The order of a reaction is determined experimentally and can be a fraction.
- C. C. Molecularity is applicable to elementary reactions only.
- D. D. Molecularity can be zero, and order of reaction must be a positive integer.
Explanation: The correct answer is D. Molecularity refers to the number of molecules involved in an elementary reaction and must be a positive integer.
Correct answer: D. Molecularity can be zero, and order of reaction must be a positive integer.- A. Increases only the rate of the forward reaction
- B. Increases only the rate of the reverse reaction
- C. Increases the rate of the forward reaction but decreases the rate of the reverse reaction
- D. Increases the rate of both the forward and reverse reactions equally
Explanation: Option D is correct. Catalysts work by lowering the activation energy required for a reaction to proceed, which affects both the forward…
Correct answer: Increases the rate of both the forward and reverse reactions equally- A. The concentration of the reactants increases
- B. The activation energy for the reaction decreases
- C. Collision frequency and energy increase
- D. All of the above
Explanation: The correct answer is that collision frequency and energy increase. When temperature increases, the kinetic energy of molecules increases…
Correct answer: Collision frequency and energy increase- A. Higher than average rate
- B. Lower than average rate
- C. Equal to the average rate
- D. None of these
Explanation: At the start of a chemical reaction, the concentration of reactants is highest, which increases the frequency of collisions between…
Correct answer: Higher than average rate- A. Rate of reaction
- B. Direction of reaction
- C. Factors affecting rate of reaction
- D. Both A & C
Explanation: Reaction kinetics is an essential branch of chemistry that examines both the rate of chemical reactions and the factors affecting these…
Correct answer: Both A & C- A. Decomposition of N2O5
- B. Formation of FeI2
- C. Formation of Glucose in plants
- D. Chlorination of methane in sunlight
Explanation: The correct answer is the formation of FeI2, as it is a second-order reaction where the rate is determined by the concentrations of both…
Correct answer: Formation of FeI2- A. 1
- B. 1.5
- C. 2.5
- D. Zero
Explanation: The order of a reaction is determined by the sum of the exponents of the concentration terms in the rate law.
Correct answer: 1.5- A. Lowering the activation energy
- B. Increasing the activation energy
- C. Lowering the frequency or effectiveness of collisions between reactive molecules
- D. Increasing the frequency or effectiveness of collisions between reactive molecules
Explanation: Increasing the temperature increases the kinetic energy of molecules, which leads to more frequent and effective collisions between…
Correct answer: Increasing the frequency or effectiveness of collisions between reactive molecules- A. A: Concentration of the reactant
- B. B: Time
- C. C: Concentration of the product
- D. D: Temperature
Explanation: The rate constant of a first-order reaction is primarily dependent on temperature.
Correct answer: D: Temperature- A. H (Enthalpy)
- B. E (Energy of Reactants or Products)
- C. Ea (Activation Energy)
- D. Collision frequency
Explanation: The correct answer is Option C: Ea (Activation Energy). A catalyst functions by offering an alternative reaction pathway with a reduced…
Correct answer: Ea (Activation Energy)- A. CH4 + Cl2
- B. CH3COOH + C2H5OH
- C. AgNO3 + NaCl
- D. C + 2H2
Explanation: The correct answer is Option C: AgNO3 + NaCl. This reaction is a classic example of a double displacement reaction where two soluble ionic…
Correct answer: AgNO3 + NaCl- A. s-1
- B. mol dm-3s-1
- C. mol-1dm3s-1
- D. mol-2dm+6s-1
Explanation: For a second-order reaction, the rate law is: Rate = k [A]^2Units of Rate = mol L^-1 s^-1Units of [A] = mol L^-1Rearranging the rate law:k…
Correct answer: mol-1dm3s-1- A. Will double the reaction rate
- B. Will increase the reaction rate
- C. Will decrease the reaction rate
- D. Will not alter the concentration of reactants
Explanation: Doubling the pressure in a liquid phase reaction typically does not alter the concentration of the reactants.
Correct answer: Will not alter the concentration of reactants- A. s-1
- B. mol-1 dm3 s-1
- C. mol-2 dm6 s-1
- D. mol dm-3 s-1
Explanation: In a third-order reaction, the rate law typically involves three concentration terms, such as [A]2[B], leading to a rate constant with…
Correct answer: mol-2 dm6 s-1- A. Option A: Nitrogen gas and hydrogen gas reacting in the presence of solid iron to form ammonia
- B. Option B: Ethylene gas reacting with hydrogen gas in the presence of solid palladium to form ethane
- C. Option C: Sulfur dioxide gas reacting with oxygen gas over a solid vanadium pentoxide catalyst to form sulfur trioxide
- D. Option D: Hydrochloric acid gas reacting with ammonia gas to form ammonium chloride
Explanation: Option D is the correct answer because in this reaction, both the reactants and the catalyst are in the gaseous phase, making it an…
Correct answer: Option D: Hydrochloric acid gas reacting with ammonia gas to form ammonium chloride- A. mol dm-3 sec-1
- B. mol-2 dm6
- C. sec-1
- D. mol-1 dm3 sec-1
Explanation: The rate of a reaction has units of mol dm-3 sec-1. For a second-order reaction, where rate = k[reactant]2, the units of the rate constant…
Correct answer: mol-1 dm3 sec-1