Q: What is the term for a certain form of matter that has the same physical properties throughout? Read this paragraph and choose the correct option from the provided answers: 8.5 End-of-Chapter Material Chapter Summary To ensure that you understand the material in this chapter, you should review the meanings of the following bold terms in the following summary and ask yourself how they relate to the topics in the chapter. A phase is a certain form of matter that has the same physical properties throughout. Three phases are common: the solid, the liquid, and the gas phase. What determines the phase of a substance? Generally, the strength of the intermolecular interactions determines whether a substance is a solid, liquid, or gas under any particular conditions. Covalent network bonding is a very strong form of intermolecular interaction. Diamond is one example of a substance that has this intermolecular interaction. Ionic interactions, the forces of attraction due to oppositely charged ions, are also relatively strong. Covalent bonds are another type of interaction within molecules, but if the bonds are polar covalent bonds, then the unequal sharing of electrons can cause charge imbalances within molecules that cause interactions between molecules. These molecules are described as polar, and these interactions are called dipole-dipole interactions. A certain rather strong type of dipole-dipole interaction, involving a hydrogen atom, is called hydrogen bonding. On the other hand, equal sharing of electrons forms nonpolar covalent bonds, and the interactions between different molecules is less because the molecules are nonpolar. All substances have very weak dispersion forces (also called London forces) caused by the movement of electrons within the bonds themselves. In the solid phase, intermolecular interactions are so strong that they hold the individual atoms or molecules in place. In many solids, the regular three-dimensional arrangement of particles makes a crystal. In other solids, the irregular arrangement of particles makes an amorphous solid. In liquids, the intermolecular interactions are Saylor URL: http://www. saylor. org/books. Choices: - balance - wave - structure - phase A:
phase

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Q: Cell communication that occurs over short distances is known as what? Read this paragraph and choose the correct option from the provided answers: Cells that are communicating may be right next to each other or far apart. In juxtacrine signaling , also known as contact-dependent signaling, two adjacent cells must make physical contact in order to communicate. Cell communication may also occur over short distances, which is known as paracrine signaling , or over large distances, which is known as endocrine signaling . Choices: - hypersignaling - contraposition signaling - cell echo - paracrine signaling A:
(Answer)
paracrine signaling

Ques: Q: What is the name of the command center of the cell? Read this paragraph and choose the correct option from the provided answers: 3.3 The Nucleus and DNA Replication The nucleus is the command center of the cell, containing the genetic instructions for all of the materials a cell will make (and thus all of its functions it can perform). The nucleus is encased within a membrane of two interconnected lipid bilayers, side-by-side. This nuclear envelope is studded with protein-lined pores that allow materials to be trafficked into and out of. Choices: - mitochondria - molecules - vacuole - nucleus A:
Ans: nucleus

(Q).
Q: Ionic liquids heating a salt to its melting point produces a what? Read this paragraph and choose the correct option from the provided answers: Molten Salts and Ionic Liquids Heating a salt to its melting point produces a molten salt. If we heated a sample of solid NaCl to its melting point of 801C, for example, it would melt to give a stable liquid that conducts electricity. The characteristics of molten salts other than electrical conductivity are their high heat capacity, ability to attain very high temperatures (over 700C) as a liquid, and utility as solvents because of their relatively low toxicity. Molten salts have many uses in industry and the laboratory. For example, in solar power towers in the desert of California, mirrors collect and focus sunlight to melt a mixture of sodium nitrite and sodium nitrate. The heat stored in the molten salt is used to produce steam that drives a steam turbine and a generator, thereby producing electricity from the sun for southern California. Due to their low toxicity and high thermal efficiency, molten salts have also been used in nuclear reactors to enable operation at temperatures greater than 750C. One prototype reactor tested in the 1950s used a fuel and a coolant consisting of molten fluoride salts, including NaF, ZrF 4, and UF4. Molten salts are also. Choices: - table salt - plasma - gas - molten salt A:
(A).
molten salt

Ques:Q: What is a layer of tissue that lies between the shell and the body? Read this paragraph and choose the correct option from the provided answers: Two unique features of mollusks are the mantle and radula (see Figure above ). The mantle is a layer of tissue that lies between the shell and the body. It secretes calcium carbonate to form the shell. It forms a cavity, called the mantle cavity, between the mantle and the body. The mantle cavity pumps water for filter feeding. The radula is a feeding organ with teeth made of chitin. It is located in front of the mouth in the head region. Herbivorous mollusks use the radula to scrape food such as algae off rocks. Predatory mollusks use the radula to drill holes in the shells of their prey. Choices: - stem - silt - node - mantle A:

Ans:mantle

Ques: Q: The enzyme pepsin works only in the presence of what? Read this paragraph and choose the correct option from the provided answers: The enzyme pepsin works only in the presence of acid. A strong acid is secreted into the stomach. It provides the acid that pepsin needs. You will learn about acids in the next chapter, "Chemistry of Solutions. " Vinegar and lemon juice are two common acids. Choices: - carbohydrates - sodium - oxygen - acid A:
Ans:
acid