the second one, I cant really tell. (The breed might help to know) But the others are girls, I am pretty sure Roo's are typically thinner and have sharper feathers, where a hens are more rounded.
The top one has a very tiny comb, just like the third one... They both have very little combs next to a few others that are the same age and size... so I assumed the others are roos, as those combs are noticeably different in size
At this age you're looking at comb and leg thickness. You can see your little cockerels have thick, stocky legs. Your pullets should have fine, thin legs. Color can also be an indicator. That little red cockerel in the last pic, you can see the start of darker shading on his wings. Hens are a more uniform color.