Which best explains what happens when an electron moves from an excited state to the ground state?

a)the electron absorbs energy as it moves to a lower energy level.
b)the electron absorbs energy as it moves to a higher energy level.
c)the electron releases energy as it moves to a higher energy level.
d)the electron releases energy as it moves to a lower energy level.

Each of the following reactions is allowed to come to equilibrium and then the volume is changed as indicated. predict the effect (shift right, shift left, or no effect) of the indicated volume change. drag the appropriate items to their respective bins.co(g) + h2o(g) < => co2(g) + h2(g) (volume is decreased) pcl3(g) + cl2(g) < => pcl5(g) (volume is increased) caco3(s)< => cao(s) + co2(g) (volume is increased)