2. Once the solution across a membrane does in fact reach equilibrium, the molecules in solution will A. move across the membrane to the outside of the cell.

B. completely stop moving across the membrane.

C. continue to move across the membrane in both directions.

D. move across the membrane to the inside of the cell.

the element that provides strength to the exoskeletons of clams and oysters is phosphorus. this is so because calcium carbonate is the main component in the shells.

explanation:

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.