Whenever i try to take the exam the screen freezes or nothing appears!!!...when i refresh..it is taking as next attempt!!!...not able to move forward...any specific browser or settings needs to be used?
First, I would check if your browser needs an update, though this shouldn't stop pages from working unless it is really out of date.
Secondly, I would clear history and cache in the browser settings, then restart your browser.
Lastly, I would double check if you have any browser extensions that are blocking or triggering any restrictions on the Anaplan website (since it is an online exam).
The other obvious thing is to keep the empty tab open so that it records and saves your process but I'm sure you're fully aware of this by now. (I can see you've kept it open in your screenshot so that's fine).
Hope this helps!