From the $1^{st},2^{nd},3^{rd}$ the $6^{th}$ statements, we can determine where Bharat and Mahesh will stay

Mahesh cannot stay in room 22 (i) nor can he stay in room 21 or 23 (ii) nor can he stay in room 25(vi). Thus Mahesh stays in room 26. Similarly, we can deduce that Bharat stays in room 21.

Now Rohan and Chirag can stay in Room 23 or 25.  But If they stay in Room 25, then Chetan will stay in room 24 (which will violate condition ii). Hence, Rohan and Chirag stay on room 23 and there are totally 2 possible cases

Sachin and Mahesh