Ques: Answer the following question given this paragraph: Insulators In contrast to metals, electrical insulators are materials that conduct electricity poorly because their valence bands are full. The energy gap between the highest filled levels and the lowest empty levels is so large that the empty levels are inaccessible: thermal energy cannot excite an electron from a filled level to an empty one. The valence-band structure of diamond, for example, is shown in part (a) in . Because diamond has only 4 bonded neighbors rather than the 6 to 12 typical of metals, the carbon 2s and 2p orbitals combine to form two bands in the solid, with the one at lower energy representing bonding molecular orbitals and the one at higher energy representing antibonding molecular orbitals. Each band can accommodate four electrons per atom, so only the lower band is occupied. Because the energy gap between the filled band and the empty band is very large (530 kJ/mol), at normal temperatures thermal energy cannot excite electrons from the filled level into the empty band. Thus there is no pathway by which electrons can move through the solid, so diamond has one of the lowest electrical conductivities known. Figure 12.23 Energy-Band Diagrams for Diamond, Silicon, and Germanium. Q: In contrast to metals, electrical insulators are materials that conduct electricity poorly because their valence bands are what? Choices: - empty - large - half-full - full A:
Ans: full

Ques: Answer the following question given this paragraph: Homeostasis, or the maintenance of constant conditions in the body, is a fundamental property of all living things. In the human body, the substances that participate in chemical reactions must remain within narrows ranges of concentration. Too much or too little of a single substance can disrupt your bodily functions. Because metabolism relies on reactions that are all interconnected, any disruption might affect multiple organs or even organ systems. Water is the most ubiquitous substance in the chemical reactions of life. The interactions of various aqueous solutionssolutions in which water is the solventare continuously monitored and adjusted by a large suite of interconnected feedback systems in your body. Understanding the ways in which the body maintains these critical balances is key to understanding good health. Q: The maintenance of constant conditions in the body is also known as what? Choices: - consciousness - mononucleosis - hypothesis - homeostasis A:
Ans: homeostasis

Ques: Answer the following question given this paragraph: Most waves approach the shore at an angle. The part of the wave that is nearer the shore reaches shallow water sooner than the part that is farther out. The shallow part of the wave "feels" the bottom first. This slows down the inshore part of the wave and makes the wave "bend. " This bending is called refraction . Q: What three characteristics do waves have? Choices: - structure , refraction and deflection - theory , refraction and deflection - spin, refraction, and deflection - reflection, refraction and deflection A:
Ans: reflection, refraction and deflection

Ques: Answer the following question given this paragraph: The arthropod exoskeleton consists of several layers of cuticle. The exoskeleton prevents water loss and gives support and protection. It also acts as a counterforce for the contraction of muscles. The exoskeleton doesn't grow as the animal grows. Therefore, it must be shed and replaced with a new one periodically through life. This is called molting . Q: What part of an animal helps to prevent water loss and gives support and protection? Choices: - membrane - cuticle - backbone - exoskeleton A:
Ans:
exoskeleton