On Ph.D. Qualifying Exams Where can I find Ph.D. qualifying exams questions.Is there any website that keeps a collection of such problems?
I need it for doing some revision of the basic topics. I know of a book but that do not have the full collection.
These are the sets of qualifying/preliminary examinations of US universities that I collected some time ago for the same purposes as you. (Dave L. Renfro points out in a commentary below that he compiled a similar list a decade ago, the following includes new departments, updated old broken links and removes unavailable sources). These exams are of much help and some even include solutions!:


University of Arizona Ph. D. Qualifying Exams
Arizona State University Qualifying Examinations
University of Alabama Qualifying Exams.
University of Alabama at Birmingham Qualifying Exams
SUNY Albany Ph.D. Preliminary Examinations.
University of California-Berkeley Preliminary Examinations.
Boston University Preliminary Exams.
University of Colorado-Boulder Prelim Exams.
Columbia University Qualifying Exams.
University of Connecticut Prelim Exams.
University of California-Davis Exams.
University of California-Irvine Exams
University of California-Riverside Exams
University of Florida Graduate Exams.
University of Georgia-Athens Qualifying Exams.
Harvard University Qualifying Exams.
University of Illinois at Urbana-Champaign Comprehensive Exams.
Indiana University-Bloomington Tier I Examinations.
University of Iowa Qualifying Exams.
Iowa State University Qualifying Exams
Johns Hopkins University Qualifying Exams.
Kansas State University Qualifying Exams.
University of California-Los Angeles Qualifying Exams.
Louisiana State University Comprehensive Exams.
University of Maryland Qualifying Exams.
University of Massachussetts-Amherst Qualifying Exams.
University of Michigan-Ann Arbor Qualifying Review Examinations.
University of Minnesota Prelim Exams.
University of Missouri-Columbia Qualifying Exams.
University of Nebraska-Lincoln Qualifying Exams.
University of New Mexico Qualifying Exams.
University of North Carolina at Chapel Hill Comprehensive Ph.D. Exams (requires one to log in).
Northeastern University Qualifying Examinations.
Northwestern University Preliminary Examinations.
Ohio State University Qualifying Exams.
Oklahoma State University Comprehensive Exams.
University of Oklahoma Qualifying Exams.
Pennsylvania State University Qualifying Exams.
University of Pittsburgh Preliminary Exams.
Purdue University Qualifying Exams.
University of Rochester Preliminary Exams.
Rutgers University-New Brunswick Qualifying Exams and oral exams.
Stanford University Qualifying Exams.
Syracuse University Prelim and Qualifying Exams.
Temple University PhD. Exams.
University of Texas at Austin Preliminary Exams.
Texas A &amp; M University Qualifying Examinations.
University of Utah Qualifying Examinations.
University of Washington Preliminary Examinations.
University of Wisconsin-Madison Qualifying Exams.
The Written Qual Book by Daryl DeFord and David Freund.