Which substance is a pure substance? salt water made from 20 g of NaCl dissolved in 80 g of H2O

a 100 g crystal of the mineral apatite (Ca5(PO4)3F)

oxygen in a container existing as O2 and O3

a steel nail made of iron (Fe) and carbon (C)

first CORRECT answer will get 50 points

In general metals get as you move from left to right across the periodic table.

Achemist at a pharmaceutical company is measuring equilibrium constants for reactions in which drug candidate molecules bind to a protein involved in cancer. the drug molecules bind the protein in a 1: 1 ratio to form a drug-protein complex. the protein concentration in aqueous solution at 25 ˚c is 1.74 x10-6 m . drug a is introduced into the protein solution at an initial concentration of 2.00 x10-6m. drug b is introduced into a separate, identical protein solution at an initial concentration of 2.00 x10-6m. at equilibrium, the drug a-protein solution has an a-protein complex concentration of 1.00 x10-6m, and the drug b solution has a b-protein complex concentration of 1.40 x10-6m.a. calculate the kc value for the a-protein binding reaction.b. calculate the kc value for the b-protein binding reaction.c. assuming that the drug that binds more strongly will be more effective, which drug is the better choice for further research?

Chortling is used to clean water. another possible atom that would also work is a. sodium b. sulfur c. bromine