What does the big ‘2’ in 2O2 mean?

I believe it means two molecules of oxygen.

Explanation:

The name for the molecular oxygen model is o2 and when you place a number in front of the element, it tells how many molecules there are of that element.  In this case, there are two molecules.

I would like to apologise in advance if this was incorrect.    

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .