Free First Law of Thermodynamics MCQs with Answers
12 First Law of Thermodynamics MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The first law states that energy is conserved, so the change in a system's internal energy equals heat supplied plus work done on the system, ΔU = q + w. Questions use sign conventions, expansion and compression work, state functions versus path functions, and the relation between internal energy and enthalpy.
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12 questions
- A. the conservation of energy
- B. the conservation of mass
- C. the increase of entropy
- D. the constancy of temperature
Explanation: Energy can be converted from one form to another but can neither be created nor destroyed, which is expressed as the change in internal…
Correct answer: the conservation of energy- A. energy is created during combustion
- B. energy is destroyed during combustion
- C. energy is transferred from the system to the surroundings but the total remains constant
- D. the enthalpy of the system increases
Explanation: The chemical energy stored in the bonds of methane and oxygen is converted into heat, which passes to the water, so nothing is created or…
Correct answer: energy is transferred from the system to the surroundings but the total remains constant- A. change in internal energy equals heat added plus work done on the system
- B. change in internal energy equals heat added minus temperature
- C. enthalpy equals internal energy divided by pressure
- D. heat equals work in every process
Explanation: The internal energy of a system can be raised either by heating it or by doing work on it, and the equation simply accounts for both…
Correct answer: change in internal energy equals heat added plus work done on the system- A. -60 kJ
- B. +60 kJ
- C. -140 kJ
- D. +140 kJ
Explanation: By the first law, the change in internal energy is the heat added to the system plus the work done on it, so 100 plus 40 gives plus 140…
Correct answer: +140 kJ- A. pressure and temperature
- B. pressure and volume
- C. heat and volume
- D. heat and work
Explanation: Heat and work are the two ways energy crosses the boundary of a thermodynamic system, and both are measured in joules (J).
Correct answer: heat and work- A. pressure and temperature
- B. pressure and volume
- C. heat and work
- D. heat and volume
Explanation: Energy crosses the boundary of a thermodynamic system mainly as heat or work, expressed in the first law as ΔU = q + w.
Correct answer: heat and work- A. At constant temperature: Q = -W
- B. When no work is done: ΔU = -W
- C. Work done on the system: ΔU = Q - P Δ V
- D. When work is done by the system: ΔU = Q - W
Explanation: The equation provided in the question follows the first convention, according to which B is not correct.
Correct answer: When no work is done: ΔU = -W- A. The thermodynamics first law is not sufficient to predict the direction of the process
- B. In the case of an exothermic reaction, the overall enthalpy fo the products is greater than that of reactants
- C. for the reaction H2(g) + Br2 (l) → 2HBr (g) from the bond enthaly data, It is possible to calculate the value of H
- D. At 298K and 1 atmpressure, diamond's standard enthalpy is zero
Explanation: Only option A has correct statement. The first law of thermodynamics states that energy is conserved in any process.
Correct answer: The thermodynamics first law is not sufficient to predict the direction of the process- 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. q = △E + W
- B. △E = q - W
- C. q = △E - P△V
- D. All of the above
Explanation: The first Law of Thermodynamics is represented by the formula: ΔE = q − W.
Correct answer: All of the aboveFirst Law of Thermodynamics MCQs: common questions
Are these First Law of Thermodynamics MCQs free?
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How many First Law of Thermodynamics MCQs are on this page?
There are 12 First Law of Thermodynamics MCQs in the Chemistry bank, shown 20 to a page with the correct answer and an explanation on each.
Does every First Law of Thermodynamics MCQ have an explanation?
Yes. Each First Law of Thermodynamics question shows the correct option and a written explanation of why it is correct, so a wrong answer teaches you something rather than just being marked wrong.
Can I take a timed First Law of Thermodynamics test?
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