Hii Divyajyoti..

As for all aspirants who look forward to took admission in IIT and NIT college ,they have to show atleast 75% in their 12 board marksheet.

As JEE Main and JEE advance's score are not based on class 12 board exam ,but during counselling ,candidate have to show their mark sheet.so candidate have to score atleast 75% in 12 board exams but for  ST or SC it is 65%.

As your score are less than 75% ,in order to increase your marks for being eligible to get admission in IIT or NIT colleges,you have to appear for improvement exam .

Now it's not necessary to give improvement exam of all subjects.There are some criteria for improvement exam:

•If a candidate passed 12 and write one or a few subject for improvement or for any reason ,then top 20 percentile cut- off will  be considered.

•However if a candidate write for all subjects then ,best of the two performance(between your original and improvement marksheet). will considered.

Hope this will help..!!

All the best dear..

Depends on scores of your individual subjects, in case you have managed to score atleast 40% marks in each of the subjects, then you can choose one or two subjects as per your choice to appear for improvement exams, but in case you have scored less than 40% in any of the subjects then I would recommend you to take improvement exam for that particular paper.

In short, you do not need to give improvement exam for all the five subjects, you can choose any one or two subjects.