All Free Chemistry MCQs with Answers
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13,720 questions · page 505 of 686
- A. +q, +w, +E
- B. -q, -w, +E
- C. +q, -w, - E
- D. -q, +w, -E
Explanation: In thermodynamics, the standard sign convention is that energy added to a system in the form of heat is treated as positive, and energy…
Correct answer: +q, -w, - E- A. 78 g
- B. 110 g
- C. 370 g
- D. 1100 g
Explanation: Now, the molar mass of water (H2O) is approximately 18.015 g/mol.The mass of ice (in grams) required to absorb this energy is:mass of ice…
Correct answer: 1100 g10083. Ho of which of the following reactions is equal to the standard enthalpy of formation of NH3?
- A. 3H2(g) + N2(g) → 2NH3(g)
- B. 2NH3(g) → 3H2(g) + N2(g)
- C. 3/2 H2(g) + 1/2 N2(g) → NH3(g)
- D. NH3(g) → 3/2 H2(g) + 1/2 N2(g)
Explanation: The standard enthalpy of formation (ΔH°f) of a compound is the enthalpy change when one mole of the compound is formed from its…
Correct answer: 3H2(g) + N2(g) → 2NH3(g)- A. H2O(s) → H2O(l)
- B. 2H2O(g) → 2H2(g) + O2(g)
- C. H2O(g) → H2O(l)
- D. Al2O3(l) + 2Fe(l) → 2Al(s) + Fe2O3(s)
Explanation: An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in an increase in the internal energy of…
Correct answer: H2O(g) → H2O(l)- A. Hvaprizaiton < Hsublimation < Hfusion < Hcondensation
- B. Hfusion < Hcondensation < sublimation < Hvaporization
- C. Hcondensation < Hfusion < Hvaporization < Hsublimation
- D. Hcondensation < Hsublimation < Hfusion < Hvaporization
Explanation: This order is generally correct. Vaporization typically requires more energy than sublimation, which requires more energy than fusion…
Correct answer: Hvaprizaiton < Hsublimation < Hfusion < Hcondensation- A. -102.4 kJ
- B. -322.1 kJ
- C. -373.3 kJ
- D. -400.0 kJ
Explanation: Let's calculate the enthalpy of the given reaction using Hess's Law. We'll use the enthalpies of the provided reactions to find the…
Correct answer: -400.0 kJ- A. -800 J
- B. -400 J
- C. O J
- D. +400J
Explanation: The change in internal energy (AU) of a system is given by the difference between the heat added to the system (q) and the work done by…
Correct answer: -800 J- A. continue to occur once started
- B. require activation energy
- C. are endothermic
- D. are exothermic
Explanation: Spontaneous reactions are those that proceed without any external intervention once initiated.
Correct answer: continue to occur once started- A. reaction of H2 with O2 to form H2O
- B. combustion of natural gas
- C. neutralization of HCI by NaOH
- D. synthesis of glucose by plants
Explanation: The process that is not spontaneous among the given options is:d. synthesis of glucose by plantsThe synthesis of glucose by plants, also…
Correct answer: synthesis of glucose by plants- A. chemical processes
- B. physical processes
- C. biochemical processess
- D. endothermic processes
Explanation: Sublimation, vaporization, melting, and photosynthesis are all examples of different physical processes.Sublimation refers to the process…
Correct answer: physical processes- A. water will vaporize
- B. ice will sublime
- C. ice will melt
- D. water will freeze
Explanation: This is correct because the amount of heat energy removed can melt approximately 0.18 g of ice.To determine what happens when 60J of heat…
Correct answer: ice will melt- A. Ti
- B. AI
- C. w
- D. Na
Explanation: The enthalpy of fusion (also known as heat of fusion) is the amount of heat required to change a substance from a solid to a liquid at its…
Correct answer: w- A. internal energy of the system increases and no work is done on the surrounding
- B. internal energy of the system increases and work is done on the surrounding
- C. no change in internal energy occurs
- D. no work is done on the surrounding
Explanation: When the volume of a system is kept constant, the process is called isovolumic or constant volume.
Correct answer: internal energy of the system increases and no work is done on the surrounding- A. spontaneous exothermic process
- B. spontaneous endothermic process
- C. non-spontaneous exothermic process
- D. non-spontaneous endothermic process
Explanation: The melting of ice at room temperature involves the transition of solid ice into liquid water.
Correct answer: spontaneous endothermic process10095. ΔH neutralization is always
- A. v
- B. -ive
- C. 0
- D. +ive or -ive
Explanation: ΔH neutralization refers to the enthalpy change associated with a neutralization reaction, which occurs when an acid reacts with a base to…
Correct answer: -ive- A. Dissolution of NH4Cl in excess of water is an endothermic process
- B. Neutralization is always exothermic
- C. The absolute value of enthalpy (H) can be determined experimentally
- D. The heat of reaction at constant volume is denoted by ΔE
Explanation: Neutralization reactions involve the combination of an acid and a base to form water and a salt.
Correct answer: Neutralization is always exothermic- A. Exothermic
- B. Endothermic
- C. May or may not be Exothormic or Endothermic
- D. None of these
Explanation: Explanation: A negative delta H value indicates an exothermic reaction, where heat is released to the surroundings.
Correct answer: Exothermic- A. delta H<0
- B. delta G<0
- C. delta S<0
- D. delta G>0
Explanation: Explanation: A spontaneous endothermic process has a negative change in Gibbs free energy (delta G<0), indicating that it can proceed…
Correct answer: delta G<0- A. Is spontaneous.
- B. Spontaneity is temperature dependent.
- C. Has an increasing free energy
- D. Is non-spontaneous
Explanation: Explanation: Whether the reaction is spontaneous or not depends on the temperature, as it influences the sign of delta G through the…
Correct answer: Spontaneity is temperature dependent.- A. thermochemistry
- B. thermodynamics
- C. chemical kinetics
- D. stoichiometry
Explanation: Explanation: Thermochemistry specifically deals with the study of energy changes in chemical systems.
Correct answer: thermochemistry