Which of these is the correct XHTML usage of the Language attribute?

Which browser does NOT support XHTML?

In the opening form tag, which is a mandatory attribute?

Which is a valid conditional statement to target all versions of IE.

Which is the correct document structure?

Which is correct application of an anchor link?

Why shouldn't you treat normally non-empty elements as empty elements (i.e., why shouldn't you use '

')?

What is the best practice for italicizing content?

Why should you make sure empty elements have a space before the close (i.e.,
instead of
)?

Minimum sufficient XHTML document, not including declarations?

Which is a correctly formatted nested bulleted list?