One I can think of immediately would be: How was your journey getting here?
Listen, they are not going to ask you to explain E=MC2, or what the chemical formula of petrol is. They will ask you about you, possibly some of your opinions, and maybe what you understand about the army and maybe some current affairs. That's it. Not rocket science. Answer HONESTLY, to the BEST OF YOUR KNOWLEDGE.
HUGE TIP: DO NOT MAKE SHIT UP - IF THEY ASK YOU TO EXPAND ON SOMETHING YOU HAVE TOLD THEM AND IT IS BS YOU WILL BE FLOUNDERING AND LOOKING STOOPID.
ANOTHER HUGE TIP: OPINIONS CAN GET YOU IN THE DOO DOO TOO, SO DON'T HAVE LARGE OPINIONS WITHOUT KNOWING THE FACTS TO BACK THEM UP. AGAIN YOU WILL LOOK STOOPID.
OP. Just be yourself and honest. Think a little bit before on why you want to join and why infantry. Don't give answers you think they want to hear, but just what you really think.
That's the best you can do. It isn't a university entrance test, it's just to look at you and see if you are suitable. So smile and be yourself because that's the person they want to see.
Oh, and be polite, and dress smartly.