Yes you can. A 12v charger can charge any 12v battery. The difference is your scooter battery is 7ah (amp hours, for those reading who may not know) and a car battery is hundreds of amp hours, so it isn't going to take very long to charge the scooter battery compared to a automobile battery. If the charger is an old analog style where you turn a knob to set the number of hours to charge, put it at the lowest setting. If it's a new digital charger, it
should know when the battery is charged and will stop charging. Over charging makes the electrolyte liquid in the batteries boil and it just kills the life of them, then they lose their ability to hold a charge. If it's charging and you hear fizzing like soda pop, the electrolyte is boiling, so stop charging.
One more note, is the age of the battery in question. If this scooter battery is 5 or more years old, and it's a lead acid battery, it may just be time for a new one. There are interesting techniques I've seen on youtube of revitalizing old lead acid batteries by dumping the electrolyte, then filling with a epsom salt solution, and getting many more years of life out of them. I have yet to try this myself, but the information is out there.