If an exception is thrown in a destructor will the data objects in the class be destructed properly?
Throwing an exception from a destructor is a bad idea and you should avoid it. The problem is that the destructor may be invoked due to another exception (as part of the stack unwinding process).
If the destructor attempts to throw an exception of its own when there is another exception being handled, the program unconditionally terminates. Furthermore, exception thrown by destructors of global objects can never be caught, because conceptually, main() has already exited when the destructor executes.