The bonds that link many water molecules together to form a water drop are: ionic
nuclear
covalent
hydrogen​

In the case of water, hydrogen bonds form between neighboring hydrogen and oxygen atoms of adjacent water molecules. The attraction between individual water molecules creates a bond known as a hydrogen bond.

covalent

Explanation:

covalent bonds occur when two atoms-in this case oxygen and hydrogen share electrons with each other

answer: oceans, duh

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.