Ques:Answer the following question given this paragraph: Chemistry is the study of matter and energy and how they interact, mainly at the level of atoms and molecules. Basic concepts in chemistry include chemicals, which are specific types of matter, and chemical reactions. In a chemical reaction, atoms or molecules of certain types of matter combine chemically to form other types of matter. All chemical reactions involve energy. Q: What is the study of the interaction between matter and energy called? Choices: - astronomy - climatology - geology - chemistry A:

Ans:chemistry
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Ques:Answer the following question given this paragraph: Water as a Component of Liquid Mixtures A mixture is a combination of two or more substances, each of which maintains its own chemical identity. In other words, the constituent substances are not chemically bonded into a new, larger chemical compound. The concept is easy to imagine if you think of powdery substances such as flour and sugar; when you stir them together in a bowl, they obviously do not bond to form a new compound. The room air you breathe is a gaseous mixture, containing three discrete elementsnitrogen, oxygen, and argonand one compound, carbon dioxide. There are three types of liquid mixtures, all of which contain water as a key component. These are solutions, colloids, and suspensions. Q: What describes a combination of two or more substances, each of which maintains its own chemical identity? Choices: - bond - structure - solute - mixture A:

Ans:mixture
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Ques:Answer the following question given this paragraph: temperature. In fact, the magnitudes of the changes in both enthalpy and entropy for dissolution are temperature dependent. Because the solubility of a compound is ultimately determined by relatively small differences between large numbers, there is generally no good way to predict how the solubility will vary with temperature. The variation of solubility with temperature has been measured for a wide range of compounds, and the results are published in many standard reference books. Chemists are often able to use this information to separate the components of a mixture byfractional crystallization, the separation of compounds on the basis of their solubilities in a given solvent. For example, if we have a mixture of 150 g of sodium acetate (CH3CO2Na) and 50 g of KBr, we can separate the two compounds by dissolving the mixture in 100 g of water at 80C and then cooling the solution slowly to 0C. According to the temperature curves in Figure 13.9 "Solubilities of Several Inorganic and Organic Solids in Water as a Function of Temperature", both compounds dissolve in water at 80C, and all 50 g of KBr remains in solution at 0C. Only about 36 g of CH3CO2Na are soluble in 100 g of water at 0C, however, so approximately 114 g (150 g 36 g) of CH3CO2Na crystallizes out on cooling. The crystals can then be separated by filtration. Thus fractional crystallization allows us to recover about 75% of the original CH3CO2Na in essentially pure form in only one step. Fractional crystallization is a common technique for purifying compounds as diverse as those shown in Figure 13.9 "Solubilities of Several Inorganic and Organic Solids in Water as a Function of Temperature" and from antibiotics to enzymes. For the technique to work properly, the compound of interest must be more soluble at high temperature than at low temperature, so that lowering the temperature causes it to crystallize out of solution. In addition, the impurities must be more soluble than the compound of interest (as was KBr in this example) and preferably... Q: What is the separation of compounds on the basis of their solubilities in a given solvent? Choices: - solvent law - fractional mass - volatile crystallization - fractional crystallization A:

Ans:fractional crystallization
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Ques:Answer the following question given this paragraph: In multicellular organisms, specialized cells may be organized into tissues. Tissues may be organized into organs, and organs may be organized into organ systems. Organ systems work together to carry out all the functions of the whole organism. Q: In multicellular organisms, specialized cells may be organized into what, which in turn may be organized into organs? Choices: - nutrients - muscles - blood cells - tissues A:

Ans:
tissues
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