In IIT-JEE 2011(Paper 1) in Section II , for a particular question say the answers are (a),(b)&(d) but I have marked say (a),(b)&(c) will marks will be rejected for marking (c) or partial marks will be awarded for (a) & (b) ? In the same paper in Section IV, for a particular question if I mark 6 & 9 as Im not sure, will marks be awarded if answer is 6 ?

no marks will be awarde in both the conditions....If u mark a,b only you will be able to get some marks but if u mark a single wrong choice then u are not elligible for any marks

For integer type questions you have to mark only one answer that also correct answer to get full marks.By marking 6 and 9 you will not get any marks.

In section 2 if you want to get partial marks you have to mark among correct choice only. If you matk wrong choice in that you will not get marks for your answer.