Hello Tejasri, 

20.33 is a very good rank in IIT JAM. You should get a seat in almost any NIT for MSC Chemistry. This includes NITs such as NIT Agartala,  MNNIT Allahabad,  NIT Calicut,  NIT Hamirpur,  NIT Jaipur,  NIT Durgapur and most other NITs.  With a rank like yours,  you will not have to worry about admission. 

For further details regarding JAM cut off, you can look here  :  https://www.google.com/amp/s/university.careers360.com/articles/ccmn-cutoff/amp

Hope this helps  :)