Why ammonia is a identified as a weak base? can you explain what it is meant by it only ionise partially?

Ammonia doesn't contain any hydroxide ions to begin, but it's dissolved in water acquires hydrogen ion from the water to produce hydroxide as well as ammonium ions. However ammonia doesn't fully convert into hydroxide and ammonium ions in solution that's why ammonia is a weak base.

in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.