You want to keep URLs as short and simple as you can. Short URLs are easier to write down on paper and easier to type in as well.
This URL...
http://www.example.com/subject/history_a/nationalism-israel-other-nations/characteristics-nationalism-national-movements-europe-19th-century/12
...is probably the 3rd longest URL I have ever seen.
The best thing to do is categorize more. Start with a domain name that best represents the exam such as:
http://www.bagrutexam.com
then you don't really need the word subject in the URL because that will be mentioned in the home page and it will be obvious in the other pages as you construct them.
Then decide on a major subject category which in your URL is history:
http://www.bagrutexam.com/history
Then if you want a subtopic, keep it short too:
http://www.bagrutexam.com/history/nationalism
Then maybe one more subtopic:
http://www.bagrutexam.com/history/nationalism/19th-century
Then a number identifying the exam itself:
http://www.bagrutexam.com/history/nationalism/19th-century/1
and for the second part:
http://www.bagrutexam.com/history/nationalism/19th-century/2
Try not to use more than two words between any two slashes in the URL or it will become very messy, and always choose the best words in the URLs that users will likely search for to reach the page.
Also, if you expect to have the URLs emailed or compatible with every device in the world regardless when it is made, then you should keep the URL length to under 80 characters.
Another disadvantage to long URLs is that too many characters will cause the server to produce its own errors. In apache, the maximum URL length is by default slightly under 8190 characters.
See: http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestline