RIDDLE 1 - They say the more things change the more they stay the same. Which dummy said that?
Get inside Joker's office adjoining the Loading Bay and take a look around the area. You need to scan the pregnancy test lying on the floor (screen above).
RIDDLE 2 - What's a funnyman without his box of tricks?
Get to the Boiler Room, which has been described in the Hot and Cold walkthrough. Here find the small box with items belonging to Joker (screen above) and scan it.
RIDDLE 3 - Once assembled, do these two become one again?
Gadgets used: Remote Electrical Charge
Start off inside the Smelting Chamber, west of the riddle area #1 #2.
Head east. On your way, you will have to unlock two doors and in both cases you need to use the Remote Electrical Charge #1 #2.
After reaching the destination, scan the Abramovici twins, sitting with their back onto you (screen above). Notice! If for some reason they aren't here, make sure that you have dealt with each of the twins in the main story mode! It also worth noticing that if you don't want to use the REC, you can also reach the twins' whereabouts from the south, going through the ventilation shaft.
RIDDLE 4 - Surely someone was clowning around when they qualified this person?
Find Joker's photos and the Gotham University diploma (screen above) and scan them all in one go.
RIDDLE 5 - Do you really need to hammer it home? Everyone knows Harley is stupid.
Stand in front of one of Harley heads (no matter whether it's already destroyed or not) and scan it together with the hammer beside it (screen above).
RIDDLE 6 - This question can only be answered from an unusual perspective. Can you get yourself there?
If you stand in the marked spot and turn on the Detective Mode, you should note an incomplete question mark #1. In order to solve this riddle you need to find the missing part and for that, head south #2.
After approaching the ledge, lower yourself (without letting go!) and use the Detective Mode to find the missing dot. The exact spot has been shown on the two above screens. Remember to place yourself in such a position that the main part of the question mark and the dot create a whole.
RIDDLE 7 - Who can BOYLE and Freeze at the same time?
Find the Boyle Cryogenics banner (screen above) and scan it.