Which form of energy listed below is the most useful?(a) 1000 J of thermal energy in very hot gas in a cylinder closed by a moveable piston (b) 1000 J of thermal energy in cold gas in a cylinder closed by a moveable piston (c) 1000 J of thermal energy in water at $15^{\circ} \mathrm{C}$ in the rocks at the bottom of a waterfall (d) 1000 J of thermal energy in the water in a boiler at $700^{\circ} \mathrm{C}$ (e) 1000 J of chemical energy stored in the chemical bonds of a piece of wood

Choose the best reason for why the following statement is incorrect: When you clean your room and decrease its disorder, you violate the second law of thermodynamics. (a) The room is an isolated system. Entropy does not change. (b) Rooms are macroscopic objects; the second law applies only to molecules. (c) The room is not an isolated system. Your work leads to considerable entropy increase.

The law of energy conservation says that energy is always conserved; it can only be transferred from one system to another or converted from one form to another. Why then do environmentalists argue for energy conservation?(a) Because they are talking about isolated systems (b) Because the environmentalists mean the energy that is useful for doing work (c) Because when a car burns fuel, its energy is used up

Choose the best slogan(s) from the physics point of view for protecting energy resources. Give the reasons for your choice. (a) Conserve energy. (b) Reduce entropy increase. (c) Conserve useful energy.

In physics the collision of billiard balls is usually considered to be elastic. What observable reason could you have for not choosing the collision of billiard balls as an example of a reversible process? (a) You hear sound produced by the collision. (b) There is change in the internal energy of the billiard balls. (c) All macroscopic processes are irreversible.

Entropy can be calculated using which of the following expressions? (a) $Q / T$ (b) $10^{6}$ (c)$\Delta Q / T$ (d) None of these