Practice SCHE0201

In a reversible adiabatic process, entropy

• increases

• decreases

• remains unchanged

• none of these

A power plant transfers 82 percent of the energy produced from burning fuel to convert water to steam. Of the energy transferred as heat by the steam, 36 percent is converted doing work through a spinning turbine. Which equation best describes the overall efficiency of the heat-to-work conversion in the plant?

• eff > 82 percent

• eff = 82 percent

• eff = 36 percent

• eff < 36 percent

If two-thirds of the energy added to an engine as heat is removed to the engine’s surroundings as heat, what is the efficiency of the engine?

• 1

• 2/3

• 1/2

• 1/3

• 0.72

• 0.39

• 0.28

• 0.22

What must be true of the combined entropy of a system and its environment?

• It increases.

• It remains constant.

• It decreases.

• It decreases at first, then increases.

An engine takes in 7.6 x 10⁵ J of energy as heat and gives up 5.7 x 10⁵ J of energy as heat to the surroundings. What is the efficiency of the engine?

• 1.33

• 0.33

• 0.25

• 0.75

Process B on the PV diagram is an ______________ process.

• adiabatic

• isobaric

• isochoric

• isothermal

When applying the first law of thermodynamics to a system, when is heat a positive quantity?

• when the system does work
• when the system has work done on it
• when the system absorbs heat
• when the system loses heat
• when no work is done either on the system or by the system

For an isothermal process, which of the following statements is correct?

• a. Work, heat, and internal energy all undergo changes.

• d. No work is done; internal energy change is due to heat.

• c. Work and heat balance each other, so that there is no change in internal energy.

• d. No energy is transferred as heat; internal energy change is due to work.

In the above image of carnot cycle step D to A shows?

• Adiabatic reversible compression

• Isothermal Compression

• Isentropic

• Isothermal Expansion