I m a student of 12^th pcm,so is it cmplsry for me to attempt biology in kvpy exam ??

No. Out of 4 ie. P C M B u have to attempt only 3, so u can attempt PCM , leaving B.

ALSO REMEMBER :

NCERT is the most important book for kvpy exam. You have to focus on the 11th ncert books.

Physics – The questions are more on general physics rather than subject knowledge. You may need to practically put the question in the situation to arrive at the answer. So right from the very beginning start thinking about why and how. Some topics like Optics and Electrodynamics of 12th are very important. So use NCERT 12th standard for these.

Chemistry – NCERT 11 is very important. Few Inorganic topics from 12th are also important

Maths – The questions are lengthy as well as logical. Previous years paper practise is important

Biology – It as biology is the easiest of all sections in the KVPY. NCERT and previous year question paper is more than sufficient