Hello Supreet Kaur, 

About the B.Arch course:

• This course is a five year full time undergraduate programme. It comprises of ten semesters. 
• The main subjects offered in this programme include architectural designs, drawings, appreciations; building construcion, management, sciences and services; theory of structurs, history of architecture, workshop practice.
• Eligibility for

Hiiii

There are a number of college providing interior designing courses. Some of them are listed below-

• Internation institute of fasion design
• JD Isntitute of fashion technology
• Apeejay Institute of design
• Pearl Academy
• LISAA school of Design

And many more..

Refe to following links for more details.
https://design.careers360.com/colleges/list-of-interior-design-colleges-in-india
https://design.careers360.com/articles/top-design-colleges-in-north-india
https://design.careers360.com/articles/know-all-about-interior-design

National Institute of Design (NID) is the best institute in India offering furniture & Interior Design course. As per the eligibility to take the admission you need to appear NID DAT Entrance Exam. You can check the eligibility of the programme with the given below link.

https://design.careers360.com/articles/nid-dat-eligibility-criteria

Regarding Interior Design

Dear Shruti,

       You can appear for CEED 2019, if you are in the final year of your Bachelors degree. In fact even if you have a diploma after your 10+2, you are eligible to appear for the entrance examination. IIT Bombay is the conducting body for CEED 2019.

For further

Hello Priyanshi,
To pursue interior designing, you should be creative and be up-to-date with the latest design trends. However, kindly let me know you are preparing for which entrance exam and you seeking admission in which college/ University?  so I can answer you accordingly.
Good Luck!

Interior designers introduce design elements and flair into interior spaces. Interior designers can be engaged to design spaces in a range of different indoor settings, including homes and businesses. You need to work on it to do the research, You can try for the internship & training programme of Austrailian

Yes 

You can definitely go for the courses in interior designing after your graduation.