What is the maximum number of electrons that transition metals can hold in their second to last shell?

How is the gravitational force related to the distance between two objects?

First answer marked as brainiest which is the correct equation describing the first law of thermodynamics? a) when the internal energy of a system changes, it equals the amount of heat added plus the work done. b) when work is done by the piston, it is equal to the heat added plus the change in internal energy of the system. c) when heat is added to the system, it is equal to the amount of work done by the piston plus the change in internal energy of the system.

Which if the following types of research is conducted on multiple occasions over time