Yes, you can use the NCERT textbooks for CBSE Class 9 as a reference for other competitive exams. Here is an explanation in detail:

1. Comprehensive Coverage:
NCERT textbooks for CBSE Class 9 are designed to provide a comprehensive understanding of the subjects. They cover all the fundamental concepts and topics in a detailed manner. This makes them a valuable resource for competitive exams as well.

2. Strong Foundation:
NCERT textbooks lay a strong foundation for various subjects. They provide a conceptual understanding of the topics, which is essential for performing well in competitive exams. By studying these textbooks, you can build a strong base of knowledge that can be applied to other exams.

3. Clarity and Simplicity:
NCERT textbooks are written in a clear and simple language, making it easier for students to understand complex concepts. They provide step-by-step explanations and examples, making the learning process more effective. This clarity and simplicity make NCERT textbooks a useful reference for competitive exams as well.

4. Widely Recognized and Accepted:
NCERT textbooks are widely recognized and accepted by educational institutions across the country. Many competitive exams also refer to NCERT textbooks while preparing their question papers. By studying these textbooks, you can align your preparation with the exam pattern and syllabus of various competitive exams.

5. Supplement with Practice Papers:
While NCERT textbooks are a great reference, it is also advisable to supplement your preparation with practice papers specifically designed for the competitive exams you are targeting. These practice papers will help you familiarize yourself with the exam pattern and enhance your problem-solving skills.

Conclusion:
NCERT textbooks for CBSE Class 9 can be used as a reference for other competitive exams due to their comprehensive coverage, strong foundation, clarity, and wide acceptance. However, it is important to supplement your preparation with targeted practice papers to maximize your chances of success in these exams.