Why simple destructor does not delete the derived object if declared using base pointer

Question

int main()
{

    Base *p = new Derived;
    delete p;
    return 0;
}

I have some confusion, why deleting p here won\'t delete the derived object ? Is

Answer 1

You should declare a virtual destructor:

class Base {
   //etc...
   virtual ~Base();
};

class Derived {
   //etc...
   virtual ~Derived();
};

Base* p = new Derived();
delete p;

(Of course many things are missing above, including constructors)