I have a friend who did his master’s from JNU and he was able to give some insight regarding the entrance test for MA Sociology. 

In the entrance examination, there will be questions from out of the syllabus. You may be asked to give a sociological interpretation of the current situation, event, etc. So, stay updated with contemporary social issues. Here is a list of sections from where you can expect questions.

• Sociological Thought: Marx, Durkheim. Weber, Parsons, Spencer, Comte, etc.
• Research Methodology and techniques
• Indian Society: Poverty, Family, Kinship, etc.
• Society and polity
• Society and economy
• Technology
• Caste and class system
• Concepts like Globalization, Modernization, Sanskritization, and Localization.

Go through the list of topics assisted to you and make sure you prepare them thoroughly. As you can see the majority of the questions are from the syllabus itself.

The NICMAT common admission test known as NCAT is of 180 marks. It comprises three sections.

1. Quantitative and Analytical Ability - 72 marks
2. Data Interpretation - 36 marks
3. Verbal and general ability - 72 marks

It is an objective paper of 1.5 hours. The syllabus is very similar to the level of SSC CGL. There is no writing portion as such

The final section is taken considering the marks in the following.

There is no technical portion in the examination, however, you may get questions out of it in the interview session. It is important to perform well in the interview session with your communication skill.

CLAT is an aptitude entrance test to get into Law institutes such as top NLU’s, NALSAR, NLIU, NUJS, etc. According to one of my friends who was in a similar situation, 4 months is a sufficient time for anyone to crack CLAT provided they study with focus, commitment. 

The ways to follow through the preparation of CLAT: -

• Joining a successful coaching institute. 
• They generally start with a crash course program in a very highly competitive atmosphere. 
• They provide the right materials, motivation for the students to excel. 
• They provide mock tests on a regular basis to see where you stand.
• Studying on your own is also an excellent choice if you know about the pattern and questions. 
• Contact any coaching for the mocks and material and get yourself enrolled in an online program. 
• Study and revise the topics through the recorded sessions as per your choice. 
• They give you all the practice material and help you devise the proper strategy to crack the exam.

It is definitely possible to crack CLAT in a 4 month time with proper guidance and dedication. So do not worry and go ahead with your decision.

One of my friends was selected for BA French at JNU a few years back and here are his tips on how to do well in the entrance exam. 

G.K: You should incorporate every little detail from Arts, Literature, Drama, Culture, Dress, Cuisines, Geography, Nobel Laureates, and more to become familiar with the language you have pursued.

Reasoning Skills: You should be proficient in solving several coding-decoding problems, especially alphabetical orders, blood relations, syllogisms, direction, and ranking tests.

English: It is equally important to be as strong in English as you are in other subjects. Various course areas, like the Basic grammatical Rules, Vocabularies, Reading Comprehension, and Passages should be on the tip of your tongue. For best results, you should follow the editorial and articles published in “The Hindu.” 

English includes a major marking scheme for all the other sections. Now, since an essay alone contains a scheme of about 20-30 marks, it is best that you practice writing ingeniously without using heavy vocabulary. JNU appreciates the artistry of innovation and it is best to keep their tastes intact. Simplicity is encouraged along the lines of critical thinking, at least more than sophisticated word formations. 

It is best to keep your thoughts perfectly aligned with the subject area, and not outside of it. 

I am not fully aware of IITs courses but could still try to give some insight of the same on whatever I got to know from the internet. 

• The ISI M.Tech CS entrance exam includes an optional Objective Paper Mathematics and a Subjective Paper (you may choose CS).
• The majority of ISI's placements are in analytics firms so it would be advised to not choose ISI if you're looking for a core CS job.
• If you are interested in Algorithm Design, Machine Learning, and, most importantly, Cryptography, then ISI would be a good option. 
• After completing your MTech CS at ISI, you will have several research opportunities in ISI and also abroad.
• ISI has excellent theoretical CS faculty (Mathematics, Statistics, Cryptography, Machine Learning, Data Science). 
• So, if you're interested in learning more about these topics, you can come to ISI.

Please do not expect to find Developer, Coder, or Core CS work at ISI after completing your M.Tech. Students have a misconception about it and come here with high hopes which ultimately backfires.

Preparation for the IISER Aptitude test will not ask for anything more than your preparation of Boards. The syllabus includes all that you studied in class 11 and 12 and for exams like JEE (mains and advanced), AIPMT, NEST. You need to keep some pointers in mind while you plan out your strategy of preparation. 

• Study Theory: You need to be very clear with all the basics in your syllabus. It is of no use to mug up all the high-level books like H C Verma and alike. Just stick to your NCERT books. 
• Once you are clear with the theory of the concepts from your NCERT books, you can look for other reference materials, notes from teachers to brush up on particular sub-topics that you need to be more sure of. You can also make your own notes since writing helps you remember things better and they can serve well in the end for revision purposes.
• When it comes to Mathematics, you can never be prepared enough or solve just the right number of problems. So, make sure to practice as much as you can since that will help you find various techniques to come up with solutions and faster of course. 

Hence, in general study and practice all the subjects- Physics, Chemistry, Mathematics, Biology and be thorough. It is okay if you did not have either Maths or Biology- don't attempt the questions you are not sure of, that will lead to negative marking. You will need to get more than 35 questions correct out of 60 in order to secure a seat at the institute.