C3H7, 86.18 g mol−1
Express your answer as a chemical formula.

13) a 14) a15) b16) i don't know sorry17) a (maybe)

Electrical charges of ionic bonds

The correct answer should be a.

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.