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 613 of 686
- A. Glycerol
- B. Isopentane
- C. Ethanol
- D. Both Options A and C are correct
Explanation: Glycerol have lower vapor pressure compared to isopentane and ethanol. Vapor pressure is a measure of the tendency of a substance to…
Correct answer: Glycerol- A. Sublimation
- B. Freezing
- C. Melting
- D. Condensation
Explanation: Evaporation is the process of a liquid changing into a gas phase. It occurs at the surface of the liquid.
Correct answer: Condensation- A. Decrease in external pressure increases the boiling point
- B. Increase in external pressure decreases the boiling point
- C. Increase in external pressure increases the boiling point
- D. None of these options are correct
Explanation: A pressure cooker is a closed container. The vapours of water formed are not allowed to escape.
Correct answer: Increase in external pressure increases the boiling point- A. Glycerol
- B. Isopentane
- C. Ethanol
- D. Both A and C
Explanation: Correct option is A. Vapor pressure depends upon the molecules that bond well and the forces of attraction of mercury metal atoms are…
Correct answer: Glycerol- A. Physical state of matter
- B. Intermolecular forces
- C. Temperature
- D. Both B and C
Explanation: The vapour pressure depends on two factors:1. Nature of liquid: The nature of liquid is explained on the basis of its intermolecular…
Correct answer: Both B and C- A. Surface phenomena is applicable.
- B. It causes cooling.
- C. Is exothermic.
- D. It is continous
Explanation: Molecules at the surface use enough energy to exceed vapor pressure and they escape in the form of gas in the air.
Correct answer: It causes cooling.- 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. Increasing the activation energy
- B. Decreasing the activation energy
- C. Increasing effective collisions
- D. Combining with reactant molecules
Explanation: The explanation for this question will be added soon.
Correct answer: Combining with reactant molecules- A. Temperature
- B. Concentration
- C. Pressure
- D. Rate constant
- E. All of the above
Explanation: The rate of reaction depends on the concentration of reactants, temperature, pressure (in case of gaseous reactants), and catalyst.
Correct answer: All of the above- A. Concentration of reactants does not affect the rate of a reaction
- B. Surface area of reactants affects rate of reaction
- C. Concentration affects rate of reaction
- D. Catalyst affects rate of a reaction
Explanation: The rate constant which is the proportionality constant that relates the rate of reaction with the concentrations of the reactants is not…
Correct answer: Concentration of reactants does not affect the rate of a reaction- A. Temperature
- B. Pressure
- C. Concentration
- D. Catalyst
Explanation: Explanation for this question will be added soon.
Correct answer: Catalyst- A. Double
- B. Three times
- C. Four times
- D. Five times
Explanation: Explanation for this question will be added soon.
Correct answer: Double- A. 74 J
- B. 10 J
- C. 116 J
- D. 106 J
Explanation: The change in internal energy (ΔU) can be calculated using the first law of thermodynamics: ΔU = Q - W Where: * ΔU is the change in…
Correct answer: 10 J- A. Second law of thermodynamics
- B. Third law of thermodynamics
- C. First law of thermodynamics
- D. Zeroth law of thermodynamics
Explanation: The law of conservation of energy states that the energy is always conserved in a closed system.
Correct answer: First law of thermodynamics- A. Equal to reactants
- B. More than reactants
- C. Always zero
- D. Less than reactants
Explanation: The total energy of products in a chemical reaction are equal to reactants according to the law of conservation of energy, which states…
Correct answer: Equal to reactants- A. CH3+
- B. (CH3)2CH+
- C. (CH3)3C+
- D. C2H5+
Explanation: Options A and D are incorrect as they are primary free radicals. Option B is incorrect as it's a secondary free radical.
Correct answer: (CH3)3C+- A. C2H4 + Cl2 -> C2H2Cl2 + H2
- B. C2H6 + Cl2 -> C2H5Cl + HCl
- C. C2H4 + Cl2 -> 2CH3Cl
- D. C2H4 + O2 -> 2CH2Cl + 2HCl
Explanation: Ethane reacts with chlorine by free radical halogenation in the presence of In the presence of sunlight, Cl2 breaks down (homolytically)…
Correct answer: C2H6 + Cl2 -> C2H5Cl + HCl