*Question*
Answer the following question given this paragraph: The canister on the left contains a gas at a certain pressure. The attached air pump is then used to double the amount of gas in the canister. Since the canister cannot expand, the increased number of air molecules will strike the inside walls of the canister twice as frequently as they did before. The result is that the pressure inside the canister doubles. As you might imagine, if more and more air is continually added to a rigid container, it may eventually burst. Reducing the number of molecules in a rigid container has the opposite effect and the pressure decreases. Q: Reducing the number of molecules in a rigid container causes what to decrease? Choices: - velocity - demand - energy - pressure A:
**Answer**
pressure

*Question*
Answer the following question given this paragraph: The first horizon is the "A" horizon. It is more commonly called the topsoil . The topsoil is usually the darkest layer of the soil. It is the layer with the most organic material. Humus forms from all the plant and animal debris that falls to or grows on the ground. The topsoil is also the region with the most biological activity. Many organisms live within this layer. Plant roots stretch down into this layer. The roots help to hold the topsoil in place. Topsoil is needed to grow most crops ( Figure below ). Q: What is the "a" horizon commonly known as? Choices: - sediment - core - crust - topsoil A:
**Answer**
topsoil

*Question*
Answer the following question given this paragraph: Viewed from Earth, Mars is red. This is due to large amounts of iron in the soil. The ancient Greeks and Romans named the planet Mars after the god of war. The planet's red color reminded them of blood. Mars has only a very thin atmosphere, made up mostly of carbon dioxide. Q: What is in the soil that causes mars to look red? Choices: - carbon - garnet - sand - iron A:
**Answer**
iron

*Question*
Answer the following question given this paragraph: Summary 16.1 Spontaneity Chemical and physical processes have a natural tendency to occur in one direction under certain conditions. A spontaneous process occurs without the need for a continual input of energy from some external source, while a nonspontaneous process requires such. Systems undergoing a spontaneous process may or may not experience a gain or loss of energy, but they will experience a change in the way matter and/or energy is distributed within the system. 16.2 Entropy Entropy (S) is a state function that can be related to the number of microstates for a system (the number of ways the system can be arranged) and to the ratio of reversible heat to kelvin temperature. It may be interpreted as a measure of the dispersal or distribution of matter and/or energy in a system, and it is often described as representing the "disorder" of the system. For a given substance, Ssolid < Sliquid < Sgas in a given physical state at a given temperature, entropy is typically greater for heavier atoms or more complex molecules. Entropy increases when a system is heated and when solutions form. Using these guidelines, the sign of entropy changes for some chemical reactions may be reliably predicted. 16.3 The Second and Third Laws of Thermodynamics The second law of thermodynamics states that a spontaneous process increases the entropy of the universe, Suniv > 0. If Suniv < 0, the process is nonspontaneous, and if Suniv = 0, the system is at equilibrium. The third law of thermodynamics establishes the zero for entropy as that of a perfect, pure crystalline solid at 0 K. With only one possible microstate, the entropy is zero. We may compute the standard entropy change for a process by using standard entropy values for the reactants and products involved in the process. 16.4 Free Energy Gibbs free energy (G) is a state function defined with regard to system quantities only and may be used to predict the spontaneity of a process. A negative value for G indicates a spontaneous process; a positive G indicates a... Q: What kind of process occurs without the need for a continual input of energy from some external source? Choices: - Decay Process - Different Process - induced process - spontaneous process A:
**Answer**
spontaneous process