Answer:
An aquifer is a layer of porous substrate that contains and transmits groundwater. ... The upper level of this saturated layer of an unconfined aquifer is called the water table or phreatic surface. Below the water table, where in general all pore spaces are saturated with water, is the phreatic zone.
Answer:
The solubility of gases decreases with pressure as that of solids and liquids is not affected.
Anything in group 18. These are the noble gases, known for having the stable octet in the outermost electron shell (with the exception of Helium). These elements include Neon, Xenon, and Radon, to name a few.
<span>Answer: a mixture.
</span><span>Justification:</span>
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</span><span>1) Pure substances have a definite chemical formula: the same kind of atoms with the same fixed ratios and chemical bonds. Therefore, the percents of each element do not varye.
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2) Elements and compounds are pure substaces. For example, Fe, Mg, Ti, are elements, and CO₂, CO, H₂CO₃ are compounds. Each of them will have always the same kind of atoms, in the same ratio and with the same chemcial bonds. Therefore the percents of the elements do not varye.
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<span>3) Mixtures are formed by the physical combination (not chemical bonds) of different elements or compounds in variable proportions. As indicated, this describes the material bronze, in virtue of the variation of its composition. Other examples of mixtures are solutions (like brines), air, ocean water, and milk: different brines, different oceans and different milk have different contents of elements or compounds.
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