Hello Arindam
I agree with what Harry has said. In addition to that, here are my further notes for you:
1. For each test, what should be an optimal number of questions? I can see I can select up to 100 questions for each of them, but I just wanted to know what should be a logically good number of questions to attempt per knowledge area before attempting the full test.
There definitely is no "optimal" number. My recommendation would instead be to look at how much time you have available. For example, if you have 1 hour available, then take a quiz with 25 questions. It will take you about 30 minutes to complete a quiz with 25 questions, and then you can spend another 30 minutes in reviewing. And this is the important part: Always spend AT LEAST the same amount of time reviewing as it takes you to take the quiz. You want to have time to go through all the questions one by one and see why you had answered incorrectly. And you want to even look at those that you answered correctly and read the explanations so that the concept will solidify in your mind.
2. Is there any list of PMBOK6 Glossary terms for each knowledge area, so that while reviewing the chapter, I could revise the glossary items too.
I have never heard of such a list and it's pretty hard to do because of how interconnected everything is. For example the term "Expert Judgment" is most likely used in every single Knowledge Area.
However, that much said, please take a look at appendix X6 of the PMBOK Guide (page 685). This appendix has a table that shows you where many of the tools are being used across the knowledge areas.
Until Next Time,
Cornelius Fichtner, PMP, CSM
President, OSP International LLC