IIT

Following are the top colleges:
Madurai Thiyagarajar College
Coimbatore Institute of Technology, Kumaraguru
SSN Kanjipuram
MIT Pune
Symbiosis Indore
BITS Pilani
BITS Goa
BITS Hyderabad.

Just check if you are getting admission in a decent institute having good placement record, known for academics. If you are not getting any good college than you can give a try for IIT.

Yes, you can apply to many universities simultaneously but you must accept only one offer. Check admission rules. Specially if you want a transfer check with them directly.

For any board you have to score more than 75% but if you failed to score this you have to be in top 20 percentile of your boards to get admission in IIT.

Kindly refer to the link mentioned below:
http://www.bestmal.com/best-books-iit-jee-chemistry/

Hello Vishakha,
For admission in IITs, target more than 130 marks in JEE Advanced if you belong to the general category.

IISc Bangalore is a better option over IITs for M.Sc and Ph.D in chemistry. It has world class facilities, faculty, research environment and industrial tie ups. IITs are good for technology education.

NITs, IIITs, DTU, NIST, IIST and state government colleges are good options for doing engineering other then IITs.

Advantage B.Tech-M.Tech dual degree is that you will be able to save one year but big disadvantage is that you will get struck with an Institute. If you do not select right Institute you do not have any corrections option available with you. If you do B.Tech from Tier 3, engineering college you can do M.Tech from top IIT by clearing GATE or do MS abroad.