Chemistry help please.

I’ve spent hours looking up information on compounds using three required text- books. The homework question that has me stumped is as follows…
“Why might some properties not be listed for all questions?” These are the ones that I could not find (Salicyclic acid, Adipic acid, Anthranilic acid, t-cinnamic acid, Heptane). I’m not looking for specific information on these individual compounds just an answer to the question. Thank you!