The last year cutoff for DU LLB for various category:

General - 91

SC - 155

ST - 202

OBC - 134; the ranks are provided as cutoff for round 1.

You can find out the cutoff marks for each round and all other years on, collegedunia.com

And the word limita for descriptive questions is 150-200. but this is not compulsory to follow. You can write more of this but stick to your topic you can get a good score.