Q: Chemical equations in which heat is shown as either a reactant or a product are called what? Read this paragraph and choose the correct option from the provided answers: 2Al(s) + Fe2O3(s) 2Fe(s) + Al2O3(s) + heat to indicate that heat is one of the products. Chemical equations in which heat is shown as either a reactant or a product are called thermochemical equations. In this reaction, the system consists of aluminum, iron, and oxygen atoms; everything else, including the container, makes up the surroundings. During the reaction, so much heat is produced that the iron liquefies. Eventually, the system cools; the iron solidifies as heat is transferred to the surroundings. A process in which heat (q) is transferred from a system to its surroundings is described as exothermic. By convention, q < 0 for an exothermic reaction. Choices: - hydroelectric equations - thorium equations - feedstock equations - thermochemical equations A:
thermochemical equations

Q: What is formed when atoms of different elements combine in a chemical reaction? Read this paragraph and choose the correct option from the provided answers: For each of the following situations, tell whether the rate of the reaction would increase or decrease, and explain your answer in terms of collision theory. The concentration of a reactant is doubled. Choices: - crystals - dust - toxins - compounds A:
compounds

Q: Plants need sunlight for what process? Read this paragraph and choose the correct option from the provided answers: The water in a large lake may be so deep that sunlight cannot penetrate all the way to the bottom. Without sunlight, water plants and algae cannot live on the bottom of the lake. That's because plants need sunlight for photosynthesis. Choices: - metamorphosis - cyclogenesis - glycolysis - photosynthesis A:
photosynthesis

Q: What happens to the electrical conductivity of metals when placed in a pot of boiling water? Read this paragraph and choose the correct option from the provided answers: levels. If a solid has a filled valence band with a relatively low-lying empty band above it (a conduction band), then electrons can be excited by thermal energy from the filled band into the vacant band where they can then migrate through the crystal, resulting in electrical conductivity. Electrical insulators are poor conductors because their valence bands are full. Semiconductors have electrical conductivities intermediate between those of insulators and metals. The electrical conductivity of semiconductors increases rapidly with increasing temperature, whereas the electrical conductivity of metals decreases slowly with increasing temperature. The properties of semiconductors can be modified by doping, or introducing impurities. Adding an element with more valence electrons than the atoms of the host populates the conduction band, resulting in an n-type semiconductor with increased electrical conductivity. Adding an element with fewer valence electrons than the atoms of the host generates holes in the valence band, resulting in a p-type semiconductor that also exhibits increased electrical conductivity. Choices: - stays the same - increases slowly - increases quickly - decreases slowly A:
decreases slowly