Question: Answer the following question given this paragraph: Solubility may increase or decrease with temperature; the magnitude of this temperature dependence varies widely among compounds. Notice in particular the curves for NH4NO3 and CaCl2. The dissolution of ammonium nitrate in water is endothermic (Hsoln = +25.7 kJ/mol), whereas the dissolution of calcium chloride is exothermic (Hsoln = 68.2 kJ/mol), yet Figure 13.9 "Solubilities of Several Inorganic and Organic Solids in Water as a Function of Temperature" shows that the solubility of both compounds increases sharply with increasing 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 Saylor URL: http://www. saylor. org/books. Q: The separation of compounds on the basis of their solubilities in a given solvent is known as what? A:
OPTIONS:
- nuclei crystallization
- simplest crystallization
- separate crystallization
- fractional crystallization
Answer: fractional crystallization

input with options: Answer the following question given this paragraph: The echinoderm nervous system has a nerve ring at the center and five radial nerves extending outward along the arms. There is no centralized nervous control. Echinoderms have separate sexes and release their gametes into the water where fertilization takes place. Echinoderms may also reproduce asexually through regeneration from body parts. Q: What process takes place when echinoderms release their gametes into the water? A:
OPTIONS:
- migration
- stimulation
- isolation
- fertilization
output: fertilization

Q: Answer the following question given this paragraph: Q: Composed largely of the polysaccharide chitin, the exoskeleton provides an effective barrier defense against most what? A:

OPTIONS:
- parasites
- white blood cells
- vaccines
- pathogens

A: pathogens

input: OPTIONS:
- 600
- 400
- 500
- 250 Now, answer this question: Answer the following question given this paragraph: Pangaea has been breaking apart since about 250 million years ago. Divergent plate boundaries formed within the continents to cause them to rift apart. The continents are still moving apart. The Pacific is shrinking as the Atlantic is growing. The Appalachians ( Figure below ) are now on a passive margin. The mighty mountains have weathered and eroded to what they are today. Q: How many millions of years ago did pangaea begin breaking apart? A:
A:
output: 250

Answer the following question given this paragraph: Accuracy describes how close an estimate is to a known standard. Q: What describes how close an estimate is to a known standard? A:

OPTIONS:
- diversity
- frequency
- precision
- accuracy

Answer: accuracy

Q: Answer the following question given this paragraph: Small nonpolar molecules can easily diffuse across the cell membrane. However, due to the hydrophobic nature of the lipids that make up cell membranes, polar molecules (such as water) and ions cannot do so. Instead, they diffuse across the membrane through transport proteins. A transport protein completely spans the membrane, and allows certain molecules or ions to diffuse across the membrane. Channel proteins, gated channel proteins, and carrier proteins are three types of transport proteins that are involved in facilitated diffusion. Q: Due to the __________ nature of the lipids that make up cell membranes, polar molecules (such as water) and ions cannot easily diffuse across the cell membrane. A:

OPTIONS:
- hydrophylic
- saturated
- catalytic
- hydrophobic

A:
hydrophobic