i am currently in class 11th and i am planning to join a test series to check my preparation in class 12th
but i am unable to decide which one would be beneficial for me.....please tell me which institues test series is the best for the preparation of iit......please answer

Askiitians online and FIITJEE are definitely the best.

Hey, actually it depends on u ...

like most people opt for fiitjee-the questions asked in their test series are very lengthy but irrelevant to the questions in jee or aieee... Personally I have tried both fiitjee and narayana ..I feel that narayana questions are to the scale . I have also opted for bansal test series ..they offer online test series and that is the best I have come across for iitjee