Which statement best describes a chemical change? O A. A substance changes size or phase.
O B. Atoms are made and destroyed.
O C. The nuclei of atoms are rearranged.
O D. Substances form new substances.

An unknown substance is a white solid at room temperature and has a melting point of 78 °c. which of the following substances is most likely to be the identity of the unknown sample?

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?

The hammering on a train track is often heard twice by workers farther down the track; first as the sound travels through the steel and second as the sound travels through the air. this suggests which graph is true?