Dear Mayank, I guess you have a little bit confusion over the subjects as only pcm marks are calculated for du in chemistry hons and even physics hons and in bsc hons physical science with chemistry. Only three subjects marks are calculated in these courses and that your pcm marks or pcb marks. If somewhere it is written for best four subjects then English will be included. Other than this there will certainly be deduction from your aggregate score.

All the best 

Hope this helps