Dear Jithin,

Depending on which board you are enrolled in the qquestion would be different. You can find model question paper for Chemistry class 12 boards on career360 and that should help you in your preparation. 

Broadly you can follow a few stratergies for your chemistry boards.

Chemistry is very broad with an extremely vast number of facts and concepts. Hence it is important that you spend time familiarizing your self with the subject.If you are from CBSE donot miss any thing in the NCERT text books.

Secondly weightage is given to equation, principles and graphs hence do emphasize  understanding the concepts in physical and organic chemistry. Questions from these chapters are going to be mostly about principles and not mugged up facts.Don't just read these chapters, practice several practice questions and papers. 

While preparing for inorganic and synthetic/biochemistry chemistry it is important to read once and recall ten times. questions from these chapters are mostly from rote learning. Again stick to NCERT only, using study guides for these chapters is just futile and a waste of time. Make several notes that will help you revise you later, especially in the time in between exams.

So I hope that this helps you. All the best for your exams.