Admission in du depends on your course as well as category. 

At 80.25% it is difficult to get into du with general category, however if you have reservation in any other category you have higher chance of getting into du.

Furthermore for science course like bsc physics hons or chemistry hons you need best of 3 rather than best of 4.

However if you want to shift to humanities you can but you will face deduction in your best of 4 ranging from 2% to 2.5%.

Thankyou.