IIT JAM

There have some serious consequences when bringing prohibited items to take any IIT JAM exams: 

Disqualification from the Exam: You can be disqualified from the exam, meaning your test could be taken away from you, and you could leave the examination room with the exam immediately invalidated. 
Seizure of Items: Any prohibited item found on your person will be taken from you by the exam officials. 
Possibly Criminal Action: Depending upon the item and the terms of the examination centre, in some cases bringing a prohibited item may incur some form of charges.

In general, no, you should not wear jewellery to the IIT JAM exam centre.

Security Checks: You are likely to have to go through security checks by way of metal detectors at the entrance. Jewellery can trigger metal detectors and causes delays, and can only be annoying at the examination.
Distraction: You may find if you wear jewellery, it can be distracting in the exam and be uncomfortable. You need to consider this and take jewellery off and leaving it at home or preventing any unnecessary issues during the exam.

You are required to carry a valid photo ID for the IIT JAM examination. Usually, the photo IDs are as follows:  
Aadhaar Card  
PAN Card  
Driving License   
Voter ID Card   
Passport  
College ID Card (with photograph)  
Any other government-issued photo ID card.

Carry original one having matching details with your admit card.

IIT JAM 2026 entrance exam does not require students to stick to a specific dress code. You can typically wear casual outfits. However by wearing a formal apparel can benefit in having a decent and presentable look (e.g., wearing a shirt and trouser).

Some institutions may have specific guidelines (e.g., wear shirts or t-shirts, jeans or trousers etc).

Candidates can review some benefits of taking IIT JAM mock Test from here:

Measure preparation ability

Develop time management strategies

Know the Exam Pattern

Firstly, go through the syllabus and keep notes attached to it. Then create a study plan and refer to quality study material like recommended textbooks make consice notes for revision. Practice regularly solve mock tests, previous year papers and solve its problems.

BONUS: Don't use your phone when you are preparing for the exam. If you're studying then keep your phone silent and stay away from unnessecary distractions.

Well, if you have Physics, Chemistry, and Mathematics, all three in your Bachelor's degree you should first understand and analyze that which subject you like the most and you are highly interested in. Then devote atleast a year and evaluate the scope of M.Sc in that particular subject, study it and then select the subject. Don't be in a rush, take your time.

Many factors affect the IIT JAM ranks:

1. Your overall score

2. Number of Applicants

3. Difficulty Level of the Exam

4. Seat Availability

5. Reservation