Hello,
Social Science in Class 9 cbse includes four sections: History, Geography, Political Science, and Economics. Typically, all books contain approximately 20-22 chapters. For MCQs, you should consult previous year question papers and sample papers, which are available on the CBSE website as well as on the websites of many educational institutions. The CBSE Class 9 syllabus generally follows the NCERT textbooks. For detailed information on Class 9 S.ST., see this article:
NCERT Books for Class 9 Social Science