Free Exothermic and Endothermic Reactions MCQs with Answers
39 Exothermic and Endothermic Reactions MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Exothermic reactions release heat to the surroundings and have negative enthalpy change, while endothermic reactions absorb heat and have positive enthalpy change. The topic uses energy profiles to identify reactants, products and activation energy, and includes bond energy, enthalpy diagrams, calorimetry and Hess's law for calculating overall heat changes.
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39 questions · page 2 of 2
- A. clay and clinker
- B. clay lime stone and gypsum
- C. lime stone and gypsum
- D. lime stone and clay
Explanation: In simplified descriptions, cement is made from calcareous material such as limestone, argillaceous material such as clay, and a small…
Correct answer: clay lime stone and gypsum- A. endothermic
- B. spontaneous
- C. non-spontaneous
- D. exothermic
Explanation: If the reactants have greater enthalpy than the products, ΔH = Hproducts - Hreactants is negative, so heat is released and the reaction is…
Correct answer: exothermic- A. endothermic
- B. spontaneous
- C. non-spontaneous
- D. exothermic
Explanation: A reaction that evolves or releases heat to its surroundings has a negative enthalpy change and is called exothermic.
Correct answer: exothermic- A. endothermic
- B. exothermic
- C. unpredictable
- D. same
Explanation: In an exothermic reaction, chemical energy is released to the surroundings, so the reactants have greater enthalpy than the products.
Correct answer: exothermic- A. Endothermic
- B. Exothermic
- C. Both a and b
- D. None of these
Explanation: The burning of fuel is an exothermic process. During combustion, the chemical bonds in the fuel molecules break, and new bonds are formed…
Correct answer: Exothermic- A. Enthalpy of atomization
- B. Enthalpy of fusion
- C. Enthalpy of neutralization
- D. Enthalpy of sublimation
Explanation: Option A: Enthalpy of atomization is the heat required to dissociate a compound into its constituent atoms.
Correct answer: Enthalpy of neutralization- A. 58 gm
- B. 56 gm
- C. 54 gm
- D. 52 gm
Explanation: Q = m x c x ΔT where, Q = heat energy required m = mass of the water c = specific heat of water ΔT = change in temperature (final…
Correct answer: 58 gm- A. In bond breaking
- B. In endothermic reactions
- C. In bond formation
- D. Both Options A and B are correct
Explanation: Breaking bonds requires adding energy, the opposite process of forming new bonds always releases energy.
Correct answer: Both Options A and B are correct- A. An endothermic reaction
- B. An exothermic reaction
- C. An isothermic process
- D. A non-spontaneous process
Explanation: This diagram shows a reaction in which the reactants are at a greater energy level than the products, indicating that energy is released…
Correct answer: An exothermic reaction- A. Endothermic reactions
- B. Exothermic reactions
- C. Exergonic reactions
- D. None of these
Explanation: A is correct as in an Endothermic Reaction, the system will absorb heat from the surrounding, hence decreasing its temperature.
Correct answer: Endothermic reactions- A. Energy released in bond breaking is greater
- B. Energy released in bond making is greater
- C. Energy absorbed in bond breaking is greater
- D. Energy absorbed In bond making is greater
Explanation: Breaking these bonds requires energy to be absorbed by the reaction. But then, new bonds form between hydrogen and oxygen and between…
Correct answer: Energy released in bond making is greater- A. Exothermic reaction
- B. Endothermic reaction
- C. Spontaneous reaction
- D. Non-spontaneous reaction
Explanation: During the enthalpy change of the solution of Na2CO3 , the temperature of the solvent rises showing that the process is exothermic.
Correct answer: Exothermic reaction- A. Exothermic
- B. Endothermic
- C. Spontaneous
- D. Non-spontaneous
Explanation: The enthalpy change of solution of sodium carbonate is -24.6kJ.mol-1. Since enthalpy change is negative, the reaction is exothermic.
Correct answer: Exothermic- A. More than 1
- B. Positive
- C. Negative
- D. Neutral
Explanation: Exothermic reaction is a reaction in which net energy is released in a reaction.
Correct answer: Negative- A. 2 H2 (g) + O2 (g) -> 2H2O (l)
- B. C(s) + O2 (g) -> CO2(g)
- C. N2(g) + O2 (g) -> N2O2 (g)
- D. None of these
Explanation: Because heat is absorbed in this reaction. All the other reactions are exothermic as the heat is released during the process.
Correct answer: N2(g) + O2 (g) -> N2O2 (g)- A. H+(aq) + OH−(aq) -> H2O(l)
- B. 1/2 H2(g) -> H(g)
- C. Na(g) -> Na+(g) + 1e−
- D. 1/2 Cl2(g) -> Cl(g)
Explanation: Explanation:Neutralization is always an exothermic reaction. Hence, the correct answer is A.
Correct answer: H+(aq) + OH−(aq) -> H2O(l)- A. C(g) + O2(g) → CO2(g)
- B. N2(g) + 3H2(g) → 2NH3(g)
- C. 2H2O(l) → 2H2(g) + O2(g)
- D. None of the above
Explanation: Explanation:This reaction is endothermic reaction: 2H2O (l) → 2H2 + O2 This reaction is Exothermic reaction, not endothermic.
Correct answer: 2H2O(l) → 2H2(g) + O2(g)- A. Thermo-chemistry
- B. Thermodynamics
- C. Electro chemistry
- D. Chemical kinetics
Explanation: Thermochemistry is the study of the heat energy which is associated with chemical reactions and/or phase changes such as melting and…
Correct answer: Thermo-chemistry- A. Exothermic
- B. Endothermic
- C. Reversible
- D. None of above
Explanation: Exothermic: An exothermic reaction is a chemical reaction that releases energy in the form of heat.
Correct answer: Exothermic