The half-life of Pa-234 is 6.75 hours. If a sample of Pa-234 contains 12.0 g, how much will remain after 27.0 hours?

Describe the interaction that occurs between two objects with the same electrical charge.

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins

Freezing and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.