can u tell the difference b/w systemexception & appllication exception ?

SystemException are predefine system exception Whereas ApplicationException are those exception which is forwarded by user program not by the CLR.

System Exceptions are the exceptions that are raised by the Framework (CLR).(e.g NullReferenceException, ArithmeticException.) These are detected by the CLR and raised. Whereas Application exceptions can also be known as custom/user induced exceptions. Application specific exceptions can be raised using Application exception. (i.e. Raise an exception to terminate the process in between, if required input data is not available)