4.15 understand that the breaking of bonds is endothermic and hat the making of bonds is exothermic

Not much to say here... when you make a bond it is an exothermic reaction, when you break a bond it is an endothermic reaction.

Energy must be supplied to break existing bonds, so bond breaking is endothermic. However, energy is released when new bonds are formed, so bond formation is exothermic.