If an atom has a mass number of 23, which of the following is always true? the number of protons in the nucleus does not equal the number of neutrons. the atomic number is less than 11. the atom is not an isotope. the atom has an odd number of neutrons.

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.