Thanks for the question. 

In order to apply for iiser, you can apply through jee channel. 

Candidates in General category securing a rank within 10000 in the Common Rank List (CRL) of JEE Advanced 2018 are eligible to apply. For candidates belonging to reserved category (OBCNC, SC, ST, PD), their category rank should be within 10, 000.

Syllabus for maths - 

Sets

Relations and functions

Trigonometric Functions

Inverse Trigonometric Functions

Principle of Mathematical Induction

Complex Numbers and Quadratic Equations

Linear Inequalities

Permutations and Combinations

Binomial Theorem

Sequences and Series

Straight Lines

Conic sections

Introduction to Three Dimensional Geometry

Limits and Derivatives

Mathematical Reasoning

Statistics

Probability

Matrices

Determinants

Continuity and Differentiability

Application of Derivatives

Integrals

Applications of integrals

Differential equations

Vectors

Three dimensional geometry

Linear Programming

For more information, you can always visit the official website of iiser 

https://www.iiseradmission.in/?page_id=8

All the best 

Dear Dharmendra,

In order to apply for IISER you can take admission through KVPY, JEE or SCB channel.

To check in detail you can refer below link

https://www.iiseradmission.in/?page_id=8

Good Luck!!