Given two entities as input, classify as "yes" if second entity is the part of the first entity. Otherwise classify them as "no". These are entities of meronym In linguistics, meronymy is a semantic relation between a meronym denoting a part and a holonym denoting a whole. In simpler terms, a meronym (i.e., second entity) is in a part-of relationship with its holonym (i.e., first entity).

Entity 1: pencil lead 
 Entity 2: pack carbon atom
yes

Entity 1: bat 
 Entity 2: crystal
no

Entity 1: brain 
 Entity 2: serotonin

yes