After establishing the response factor of the instrument, the researcher collected 13.97 g of spinach, homogenized the sample, and extracted the DDT using an established method, producing a 3.87 mL solution containing an unknown amount of extracted DDT. The researcher then prepared a sample for analysis that contained 0.500 mL of the unknown DDT solution and 1.25 mL of 10.37 mg/L chloroform, which was diluted to a final volume of 25.00 mL. The sample was analyzed using GCMS, producing peak areas of 7583 and 15019 for the DDT and chloroform, respectively. Required:

Calculate the amount of DDT in the spinach sample. Express the final answer as milligrams of DDT per gram of spinach.

Which statement describes the appearance of a temperature-vs.-time graph? a horizontal line shows that the temperature increases at a constant rate over time. a vertical line shows that the temperature decreases at a constant rate over time. horizontal lines where the temperature is constant during phase changes connect upward-sloping lines where the temperature increases. horizontal lines where the temperature increases are connected by upward-sloping lines where the temperature is constant for each phase.

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

The number of neutrons is equal to the atomic number minus the atomic mass. a. true b. false