You are concerned about the rate of death in catfish your aquaculture operation in tanks that have a high amount of algae growth. You collect some of the algae and send it to the university to have it identified. You find that it is a blue-green alga called Anabaena. Anabaena is known to be toxic to fish. You design an experiment to test how much of the algae the fish can stand before they die. You obtain 6 large aquariums (all the same size) and fill them with water taken from a healthy catfish pond at your operation. You put each aquarium on the same bench in the laboratory, where the light and temperature values are identical. You let the water stand for one day before starting the experiment. In aquarium 1, you add 2 grams of algae and no fish. In aquarium 2, you add 20 small catfish and no algae. Aquarium 3 gets 20 catfish and 2 grams of algae, #4 gets 20 catfish and 4 grams of algae, #5 gets 20 catfish and 8 grams of algae, and aquarium #6 gets 20 catfish and 16 grams of algae. The aeration rate of each aquarium is identical. You make two observations at the same time each day for two weeks. You keep track of the numbers of fish in each tank that die. What is the problem? What is your hypothesis? What is the independent variable? What is the dependent variable?

The diagrams show objects’ gravitational pull toward each other. which statement describes the relationship between diagram x and y? gravity attracts only larger objects toward one another. gravity attracts larger objects only if they are close to one another. if the masses of the objects increase, then the force between them also increases. if distance between the objects increases, then the amount of force also increases.

Find the midpoint of a segment with endpoints of 4-3i and -2+7i

1.) which of the following is a molecule but not a compound? a. he b. f2 c. h2o d. ch4 2.) what is a physical combination of substances? a. a compound b. a molecule c. a mixture d. an element 3.) what is a chemical combination of substances? a. a compound b. an atom c. a mixture d. an element 4.) what is the relationship between the solute and solvent in a solution? a. they form a compound b. they form a mixture c. they form molecules d. they form chemical bonds 5.) the gases in air dissolve in water. what would be one way to reduce the amount of a gas dissolved in water? a. add more water b. reduce the air pressure c. increase the air pressure d. stir the water 6.) how would you determine the solubility of a substance? a. find how well it dissolved various substances. b. find the mass and the volume of the substance. c. find the temperature at which the substance evaporated. d. find how much i was able to dissolve in a solute. 7.) the periodic table organizes all of the kinds of a. molecules. b. compounds. c. atoms. d. ions. 8.)what distinguishes two substances combined to become a compound vs. two substances combined to become a mixture? a. whether they can be easily separated b. whether they chemically bond together c. whether they both are visible d. whether they are heterogeneous 9.) the principle components of air are: n2 78% o2 21% ar 0.95% co2 0.038% this is a solution of a. molecules and atoms. b. molecules. c. compounds and molecules. d. atoms.