Dear Student,

No, It's not mandatory of having Computer Science as a compulsory subject in class 11 , 12th or 9 , 10th ..

Well, if you're interested in CSE domain in B.tech , then taking Comp sc. in class 11 will be useful for you , as through this subject you'll get a basic concept of computer architecture and its related properties and can learn several programming languages as beginner level which will help you to grab the advance concepts of computer science in CSE domain.

For more details about Computer science courses , refer this :

https://www.careers360.com/courses/computer-science-engineering-course

Hope this helps !