Can I use a 12 volt charger to charge a 9.6 volt battery pack.?

The Charger output is 12v 1200mah, and I want to charge a 9.6 NI-MH 3500mah battery pack. If I'm able to charge the pack could you tell me how long it would take to charge. Could I also charge 8.4 volt NI-CAD/NI-MH battery packs with it?