Answer the following question given this paragraph: The table salt pictured in the Figure below contains two elements that are so reactive they are rarely found alone in nature. Instead, they undergo chemical reactions with other elements and form compounds. Table salt is the compound named sodium chloride (NaCl). It forms when an atom of sodium (Na) gives up an electron and an atom of chlorine (Cl) accepts it. When this happens, sodium becomes a positively charged ion (Na + ), and chlorine becomes a negatively charged ion (Cl - ). The two ions are attracted to each and join a matrix of interlocking sodium and chloride ions, forming a crystal of salt. Q: Another name for table salt is? Choices: - hydrogen chloride - carbon chloride - dioxide chloride - sodium chloride A:
sodium chloride
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Answer the following question given this paragraph: Supercritical Fluids If we place a sample of water in a sealed container at 25 C, remove the air, and let the vaporization-condensation equilibrium establish itself, we are left with a mixture of liquid water and water vapor at a pressure of 0.03 atm. A distinct boundary between the more dense liquid and the less dense gas is clearly observed. As we increase the temperature, the pressure of the water vapor increases, as described by the liquid-gas curve in the phase diagram for water (Figure 10.31), and a two-phase equilibrium of liquid and gaseous phases remains. At a temperature of 374 C, the vapor pressure has risen to 218 atm, and any further increase in temperature results in the disappearance of the boundary between liquid and vapor phases. All of the water in the container is now present in a single phase whose physical properties are intermediate between those of the gaseous and liquid states. This phase of matter is called a supercritical fluid, and the temperature and pressure above which this phase exists is the critical point (Figure 10.35). Above its critical temperature, a gas cannot be liquefied no matter how much pressure is applied. The pressure required to liquefy a gas at its critical temperature is called the critical pressure. The critical temperatures and critical pressures of some common substances are given in Table 10.3. Substance. Q: What phase exists when all the water in a container has physical properties intermediate between those of the gaseous and liquid states? Choices: - stationary fluid - hydrothermal fluid - impregnation fluid - supercritical fluid A:
supercritical fluid
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Answer the following question given this paragraph: An acid-base indicator is a substance that displays different colors when in the presence of an acid or a base. How does that work? An indicator is a weak acid that ionizes within a known pH range, usually about 2 pH units. We can represent the protonated form of the indicator molecule as HIn and the deprotonated form as In . The following equilibrium exists for the indicator. Q: A substance that displays different colors when in the presence of an acid or a base is called what? Choices: - pH scale - reactor - litmus test - an acid-base indicator A:
an acid-base indicator
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Answer the following question given this paragraph: Local winds are winds that blow over a limited area. Local winds blow between small low and high pressure systems. They are influenced by local geography. Nearness to an ocean, lake, or mountain range can affect local winds. Some examples are found below. Local winds can affect the weather and climate of a region. Q: What are winds that blow over a limited area called? Choices: - trade winds - Planetary Winds - Periodic Winds - local winds A:
local winds
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