Which elements make up most organic compounds?
a.
carbon and hydrogen (also oxygen, nitrogen, phospohorus, and sulfur)
b.
helium, neon, and argon
c.
carbon and krypton

The internal energy of the system we can term it as total potential energy and kinetic energy. energy flows out of the surrounding from the system then we can say that the internal energy of the final state is lower than its initials. the sign of  δesystem is negative.δesystem = efinal - einitial=-ve  efinal  ∠einitial.