Chemistry questions and answers are available for free at websites for Just Ask Antoine!, About.com, Yeah Chemistry and Cliff's Notes. College Board offers questions and solutions from AP chemistry exams prior to Spring 2013.
Professor Fred Senese, from the Frostburg State University Department of Chemistry, answers general chemistry questions on "Just Ask Antoine!" The site includes a searchable or browsable archive of more than 400 questions and answers about topics including organic chemistry, quantum theory and the periodic table.
Moderated by Anne Marie Helmenstine, Ph.D., the chemistry section at About.com offers several question and answer articles, including topic-specific tests, quizzes and sample chemistry problems.
As of March 2015, Yeah Chemistry provides a browsable list of more than 12,000 previously answered questions, including links to the direct answer and each question's general topic. Users are also able to search the Yeah Chemistry archive by specific topic or keyword.
Cliff's Notes has a browsable list of general science questions and answers, including chemistry subjects. The site covers general topics ranging from chemical composition to photosynthesis and chemical equations.
College Board offers a single list of past multiple choice questions from part I of the AP chemistry exam. The site also offers section II questions and answers from past exams between 1999 and 2013. Each exam includes three quantitative problems, one covering chemical reactions and two essays discussing specific laboratory or quantitative topics.