Here are some random tasks that I quite can't wrap my head around. Instructions: There are two rule-based categories in each of these 5 puzzles, marked with either black or grey dots. To which category do the uncategorized (white-dotted) items belong and why?

My problem with task 1 is for instance that the black-dotted items all have "Z", but if the rule is "exactly four Z", the most-right uncategorized item should be grey (it has five), but if the rule is "at least four Z" the item should be black.

Task 1

Task 2

Task 3

Task 4

Task 5