18) Which two ions have the same electron configuration in the ground state? A) Rb+ and Cs+
B) Ba2+ and I-
C) Se2+ and I-
D) Fe2+ and Fe3+

1. suppose a reaction mixture, when diluted with water, afforded 300 ml of an aqueous solution of 30 g of the reaction product malononitrile [ch2(cn)2], which is to be isolated by extraction with ether. the solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water is 13.3 g/100 ml. what weight of malononitrile would be recovered by extraction with (a) three 100-ml portions of ether and (b) one 300-ml portion of ether? suggestion: for each extraction, let x equal the weight extracted into the ether layer. in part (a), the concentration in the ether layer is x/100 and in the water layer is (30 x)/300; the ratio of these quantities is equal to k 20/13.3.

98 points you will be galileo perform the experiment to determine if objects with different mass fall at the same, or different, rates in the air and in a vacuum. before you conduct your experiment, you need to form a hypothesis. a hypothesis is a prediction of what you think will happen in the experiment. the hypothesis is a statement that describes “if” a certain set of circumstances are present “then” there will be a specific result that will occur. record your hypothesis here: record the results from step one of the experiment (dropping the objects in the air): first trial: second trial: third trial: record the results from step two of the experiment (dropping the objects in a vacuum): first trial: second trial: third trial: did the experiment support your hypothesis? using the data from your experiment, describe why you believe your hypothesis was either proven or disproven. what forces were acting on the objects dropped in the air? what force was acting on the objects dropped in the vacuum? part two: comparing forces choose two forces and compare and contrast these forces. you must provide two ways that they are alike and two ways that they are different. you may make a list, write in paragraph form, or make a chart. choose two forces and compare and contrast these forces. these must be different forces than used in the prior question. provide two ways that they are similar and two ways that they are different. you may make a list, write it out, or make a chart.

How is energy related to the change of state represented by the model? atoms gain energy as a solid changes to a liquid. atoms gain energy as a solid changes to a gas. atoms lose energy as a solid changes to a liquid. atoms lose energy as a solid changes to a gas.