How much of an 800-gram sample of potassium-40 will remain after 3.9 x 109 years of radioactive decay?

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.

Achange in the number of neutrons in an atom will change an blank . when the number of protons changes in an atom, a new element will form.

0.2348 grams of pbcl2 used to form 44.0 ml of solution.