This seems to be the case for every emergency exit I've passed through. Maybe its a Sydney thing..?
i failed my dmv first try because of this reason.. No, you didn't. It takes multiple faults to fail a driving test. So you failed several other areas, including this one. the lady was dumb You mean the driving examiner. And it would do well for you to listen to her, seeing as she's the one who passes or fails you. Instead of calling her dumb, take her advice. Drive faster. If the next person fails you, have them document your speed on that section, and keep a copy. You can dispute it at that point, if need be.
If it is installed correctly, ABSOLUTELY ZERO. Probably not, at least you would get burned. You can obviously check it. There will be a brass colored valve on top of the tank. Attached to that will be a pipe. If the pipe is not capped off, ALL is good and it won't blow up on you.
You could take the batteries out but I doubt you would be able to get it off the wall. They will charge you for any damages so just pay more and get a smoking room. If you are old enough to rent out a room and smoke then you should be wise enough to know the consequences.
Hot water tanks have pressure relief valves to keep from exploding. Also, the tank is full of hot water, so it cannot explode. Only if someone alters the tank, to scare people like you, will the tank explode. {Tank only partially full, no relief valve, and enough energy to make many atmospheres' pressure of steam would make the steel shell rip apart.} If someone turns on the hot water faucet and steam comes out, they/you have warning that something is wrong. Just leave the faucet open, and turn off the energy source (gas or electricity). You are perfectly safe in your bedroom. If not worrying is not an option, then pray every night before you go to bed. Sweet dreams.