sir/mam sorry to ask again i came to know that if you have a rural citizen or SC/ST certificate then u'll got 3 chances in IIT

No as far as I know there is no such rule at present.

Rahul- IIT Roorkee

You should go for concentrating all the three subjects equally.Give less time on your strong subject because you can grab the concepts fast and spend more time on your weak subjects(or topics).

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