#'s 1-4 -- roos
#5 - pullet
#6 - pullet? (can't see the comb very well)
#7 - roo
This is a photo of my 7-8 week old RIR/PR & leghorn pullets - any of your chicks that already have a bigger comb & wattles (at only 4 1/2 weeks) than the chicks in this pic are probably roos.