Naina
I wish I could help. I cleared XML exam early this year and have been less interested in Qs and As for XML certification. If you are reasonably familiar with XML, sit down with a book and take the sample exam. Assuming you can at least 10-15 correct without help, you can always look up the reference for other questions. Like the actual exam you are limited only on total time - you can spend any long on individual questions.
Anyway you are not looking to score 100% which anyway is of little value. Just ensure that you have a few more correct than the minimum needed to pass. I am not sure if vouchers are still available. Usually IBM posts in News link in
www.ibm.com/certify when vouchers get exhausted. But those days the vouchers were based on passing free exams. If they publish that vouchers are no longer available, $10 per exam may also dry up.
XML is not a very difficult exam. I still feel it is one of the easier IBM exams. Nevertheless you need to be prepared because the scope of the exam is very wide and exams do get revised without notice to candidates.
My best wishes to you.