As the plate 2 is common plate for two capacitors and connected to the negative terminal of battery so its charge should be −(q+q)=−2q.
Similarly plate 3 is also common plate between two capacitors and connected to the positive terminal of battery so its charge should be +(q+q)=+2q.
Similarly for plate 4, charge on it =−(q+q)=−2q
Plate 5 is not common plate between two capacitors and connected to positive end of battery. Thus its charge =+q