Hi 
There are numerous sites that provide IIT JEE questions. Askiitians also offer the Mock test papers for IIT JEE. 
IIT JEE Mock Test

IIT JEE being a very competitive exam needs constant practice and reiteration of concepts. While you are solving IIT JEE mock test questions in a real IIT JEE environment you get the knack of solving these questions. 
Time and again the toppers advise students to practice tests from different chapters in a timed environment and keep on self evaluating their performance. AskIITians online mock test series does exactly the same for you. 
You get real IIT JEE like question papers which are set keeping in mind the latest pattern by our esteemed faculty. Faculty at askIITians has been known for its exact IIT JEE like questions and mock test for Maths, Physics and Chemistry. Also that’s what makes us most popular choice for preparation for all engineering entrance exams. 
Practice tests series at askIITians will not only help you evaluate yourself but also help you compare with what your peers are doing. askIITians also provide you full detailed answers and solutions of all these questions so that you can check your work with that done by our experts. 
We also provide you free email assistance, so if you are stuck while solving any question or you have a particular doubt which you want to clarify with our experts then please feel free to write to us at info@askiitians.com and all your queries will be responded within 24 hrs. 
You can also find last year JEE papers and their solution from the foll site www.iitjee.org/iit-question-papers/iit-papers.html