Yes why not it is absolutely able to study both for HSC and NEET examination simultaneously because many students have successfully done that even I myself have done so just one thing I would like to tell you that you should not much focus on the board examination just study till you pass and you are eligible to appear for NEET examination give more focus on NEET examination because it is more important than boards to enter medical college.

• Since you will get 2 months before NEET after your boards so keep that time for 11th class syllabus.
• For now study 12th syllabus but as per NEET preparation and as per boards cause boards are automatically prepared if you are preparing like NEET.
• For organic chemistry you can't expect to understand 12th organic property if you don't have a strong grasp on 11th class basic concepts so firstly focus on basic concepts of organic chemistry then jump to 12th syllabus so to have better understanding.

hi satyam pandey, you still have 5 months time and if you work smart, you can really score well easily, i will tell you how to prepare 

Physics and chemistry- physics is considered one of the toughest subject for medical aspirants,but very interesting. choose any good book of your convinience, there are plenty of good books as many mentioned already. read the concepts thoroughly,understand them cover to cover, if you have doubts, clear them then and there. solve atleast 300 to 500 questions per chapter, check ,analyse and rectify your mistakes. solve again. the more you solve the merrier.initially you wont be getting many correct answers, but as you keep on doing am sure you will see your score rising. solve previous question papers too

Biology- in neet around 300 marks are from ncert text book itself,thats how it was when i gave my exam, so u need to thorough ncert first and then read any good book of your choice and solve as many questions as you can, always stay calm , cool and confident,hope this helps good luck buddy

Please check the below link for Tips on how to prepare for NEET and which books to refer

https://www.entrancecorner.com/medical/preparation-tips-for-neet-2018/