As per the exam pattern released by Council of Architecture for NATA 2020, there will be total 15 questions from Physics, Chemistry and Mathematics while 35 questions will be asked from General Aptitude and Logical Reasoning. That means more importance and weightage will be given to General Aptitude and Logical reasoning section. For Physics, Chemistry and Mathematics, you can follow NCERT txtbooks of class 11 and 12 as these books are best for basic preapartion and concept clarification. Few questions are directly asked from the NCERTs itself. For complex problems you can follow HC Verma for Physics, RC Mukherjee for Chemical Calculations and RD Sharma for Mathematics. There is no negative marking. The most important part in the NATA examination is the Drawing Test where 10 questions will be asked. You should practice more for the Part A as it carries more marks.