Hey Gayatri, 

Mop up round is the final round of NEET counselling  in this round all the left over seats, unalloted seats and surrendered seats are offered to the interested meritaceous students  most of the time this round is left with minority seats. 

Eligibility for Mop up round : The candidates who have not been alloted any seat in first and second round of counselling . 

For getting any information regarding Karnataka NEET counselling, kindly refer this link :
https://medicine.careers360.com/articles/karnataka-mbbs-counselling
Good Luck!