i am a science(maths) stream student not interested in doing engineering what else can i do and if bcom is tough for science student

no it is not tough in account you will have to give some extra effort

you can do B.SC(more trades are available).Now come to B.com yes u can do but you don't know the basics of accounts,bussiness the main topic of B.com.you must contact your seniors,teachers.Best of Luck for your bright future.