Language : Sir, In B. Sc, all subjects are in hindi or english? I prefer hindi because i pass my 12th class in hindi...

Dear student,

That depends upon which college you are taking admission in. If you take admission in an English medium college, then the subjects and lessons will be taught in Englsih & vice-versa. 

But local influences play a huge role...Meaning, if most of the students are native language speakers, then by default, the professors also teach in a mixed language.  You should first identify the college where you want to take admission in and then find out details.