CSC Chennai interview questions

I had an interview with CSC chennai last week, following are the questions asked to me:
- Which desing pattern you follows?
- What is kept in desing document?
- Which default functions are created in empty class?
- What is the need of overloading a copy constructor?
- Does default constructor invoked by default copy constructor?
- How to limit number of instances of class? or How to track running instances of a class?
- Three overloaded constructors:
class A
{
A();
A(int i);
A(int i = 10);
}
Is there any problem with this?
What will happen if 'A()' is removed due to ambiguity and 'A a2(10);' will invoke which constructor?
- How to print a linked list in reverse order?
- Inheritance:
class A
{
virtual void f1();
}
class B : public A
{
virtual void f1();
virtual void f2();
}
B *b = new A;
b->f1();
b->f2();
What will be the problem? How to invoke 'f2()' using using object of class A.
[ Actually this question was wrong or I heard this question as wrong]
- Two buckets of 5 liter and 3 liter. How to major 4 liter of water?