.NET XML Question

1. What is the use of XML Namespaces?
2. When is the DOM appropriate for use? When is it not? there is any size limitations?
3. What is the WS-I Basic Profile?
5. What is the fundamental difference between Elements and Attributes?
6. What is the difference between Well-Formed XML and Valid XML?
7. How would you validate XML using .NET?
9. Describe the difference between pull-style parsers (XmlReader) and eventing-readers (Sax)
10. What is the difference between XPathDocument and XmlDocument?
11. What is the difference between an XML "Fragment" and an XML "Document."
12. What does it meant to say “the canonical” form of XML?
13. Why is the XML InfoSet specification different from the Xml DOM? What does the InfoSet attempt to solve?
14. Contrast DTDs versus XSDs. What are their similarities and differences? Which is preferred and why?
15. Does System.Xml support DTDs?
16. Can any XML Schema be represented as an object graph? Vice versa?