Do Sample Question Papers change every year? Why?

The changes are not random; they are made for several important reasons:

To Reflect Syllabus Changes 
The syllabus is often updated with additions, deletions, or modifications to topics.1 The new SQP is released to align perfectly with the current and official syllabus for that academic year.

To Introduce New Question Patterns 
CBSE continuously evolves its assessment methods. In recent years, there has been a major shift towards competency-based questions (like MCQs, case studies, and assertion-reasoning). The SQP is the primary tool the board uses to show students and teachers the new question typology and the weightage of each type.

To Adjust Difficulty and Focus 
The board might decide to change the weightage given to different chapters or adjust the overall difficulty level of the paper. The SQP signals these shifts, helping students focus their preparation accordingly.

To Ensure Fairness and Prevent Rote Learning
If the pattern remained identical, students might just practice a fixed set of questions. By introducing variations, CBSE encourages a deeper conceptual understanding rather than rote memorization of formats.

The SQP is a dynamic and essential communication tool. It ensures that students are preparing for the exam as it will be conducted this year, not last year.