Answer the following question given this paragraph: Phase and Surface Area Effects When two reactants are in the same fluid phase, their particles collide more frequently than when one or both reactants are solids (or when they are in different fluids that do not mix). If the reactants are uniformly dispersed in a single homogeneous solution, then the number of collisions per unit time depends on concentration and temperature, as we have just seen. If the reaction is heterogeneous, however, the reactants are in two different phases, and collisions between the reactants can occur only at interfaces between phases. The number of collisions between reactants per unit time is substantially reduced relative to the homogeneous case, and, hence, so is the reaction rate. The reaction rate of a heterogeneous reaction depends on the surface area of the more condensed phase. Automobile engines use surface area effects to increase reaction rates. Gasoline is injected into each cylinder, where it combusts on ignition by a spark from the spark plug. The gasoline is injected in the form of microscopic droplets because in that form it has a much larger surface area and can burn much more rapidly than if it were fed into the cylinder as a stream. Similarly, a pile of finely divided flour burns slowly (or not at all), but spraying finely divided flour into a flame produces a vigorous reaction (Figure 14.3 "The Effect of Surface Area on Reaction Rates"). Similar phenomena are partially responsible for dust explosions that occasionally destroy grain elevators or coal mines. Q: Do particles collide more in two reactants when they are both in fluid forms or solid forms? Choices: - plasma - neither - solid - fluid A:
fluid
(Question)
Answer the following question given this paragraph: Bases often have a bitter taste and are found in foods less frequently than acids. Many bases, like soaps, are slippery to the touch. Q: What type of taste do bases normally have? Choices: - sour - salty - sweet - bitter A:
(Answer)
bitter
Ques: Answer the following question given this paragraph: A mantle , or fold of the outer skin lining the shell. The mantle often releases calcium carbonate, which creates an external shell, just like the ones you find on the beach. The shell is made of chitin , a tough, semitransparent substance. Q: What is a fold of the outer skin lining the shell called? Choices: - marble - cortex - stack - mantle A:
Ans: mantle
(Q).
Answer the following question given this paragraph: The reactants are two electrically neutral elements; they have the same number of electrons as protons. The product, however, is ionic; it is composed of Mg2+ and Clions. Somehow, the individual Mg atoms lose two electrons to make the Mg2+ ion, while the Cl atoms gain an electron to become Cl ions. This reaction involves thetransfer of electrons between atoms. The process of losing and gaining electrons occurs simultaneously. However, mentally we can separate the two processes. Oxidation is defined as the loss of one or more electrons by an atom. Reduction is defined as the gain of one or more electrons by an atom. So oxidation and reduction always occur together; it is only mentally that we can separate them. Chemical reactions that involve the transfer of electrons are called oxidation-reduction (or redox) reactions. Redox reactions require that we keep track of the electrons assigned to each atom in a chemical reaction. How do we do that? We use oxidation numbers to keep track of electrons in atoms. Oxidation numbers are assigned to atoms based on four rules. Oxidation numbers are not necessarily equal to the charge on the atom (although sometimes they can be); we must keep the concepts of charge and oxidation numbers separate. The rules for assigning oxidation numbers to atoms are as follows: 1. Q: What is the term for the loss of one or more electrons by an atom? Choices: - half-life - decomposition - evaporation - oxidation A:
(A).
oxidation
Ques:Answer the following question given this paragraph: Homeostasis The goal of homeostasis is the maintenance of equilibrium around a specific value of some aspect of the body or its cells called a set point. While there are normal fluctuations from the set point, the body's systems will usually attempt to go back to this point. A change in the internal or external environment is called a stimulus and is detected by a receptor; the response of the system is to adjust the activities of the system so the value moves back toward the set point. For instance, if the body becomes too warm, adjustments are made to cool the animal. If glucose levels in the blood rise after a meal, adjustments are made to lower them and to get the nutrient into tissues that need it or to store it for later use. When a change occurs in an animal's environment, an adjustment must be made so that the internal environment of the body and cells remains stable. The receptor that senses the change in the environment is part of a feedback mechanism. The stimulustemperature, glucose, or calcium levelsis detected by the receptor. The receptor sends information to a control center, often the brain, which relays appropriate signals to an effector organ that is able to cause an appropriate change, either up or down, depending on the information the sensor was sending. Q: The human body wants to maintain equilibrium or balance, also known as what? Choices: - perfection - heterostasis - stability - homeostasis A:

Ans:homeostasis
Question: Answer the following question given this paragraph: Ginkgo trees are gymnosperms with broad leaves. Q: Ginkgo trees are gymnosperms with broad? Choices: - trunks - roots - fruits - leaves A:
Answer:
leaves