2 is a pulletThey are now 10 weeks old. What are your thoughts now? Number 5 acts like a rooster. The other 3 do have smaller frames.
3 is most likely a pullet
5 is a cockerel
1 and 4 are still questionable. Keep an eye on comb size/color. Any growth spurts and reddening in that area in the next 4 or 5 weeks means you likely have cockerels.