if I prepare in just 25 to 26 days in this remaning day's can I score 240 marks in neet 2020

Scoring 240-250 marks cannot be that difficult. Stick to NCERT books and practise atleast one mock test a day.

In Physics, Highest weightage goes to Optics at 10%. Thermodynamics, Electrostatics, Electronic devices share 9%. Current Electricity and Electromagnetic induction, Alternating current take 8%. Dual Nature of Radiation gets 6% while Motion systems of rigid particles and body and Magnetic effects of Currents, Electromagnetic waves and Magentism get 5%. Work, Energy and Power take 4%, Atoms and nuclei, Oscillation and Waves, Properties of Bulk Matter, Laws of Motion and Kinematics share 3% and the rest of the topics carry 2% weightage.
10% is 6-7 questions, 9% is 4-5 questions, 7% is 3 questions, 4- 5% is 2 questions , 2-3% is 1 question.
In Chemistry, Coordination points get 9% of weightage. Thermodynamics takes the 8% and Equilibrium takes the 6% weightage slots respectively. Chemical Bonding and Organic structure carries the 5% weightage slot and rest of the topics carry 2-3% weightage in the exam paper.
10% is 6-7 questions, 9% is 4-5 questions, 6-7% is 3 questions, 4- 5% is 2 questions , 2-3% is 1 question.
In Biology, Diversity of Living Organisms has 14% weightage. Structural Organisationi n Plants and Animals takes 5%. Plant Physiology has 6% and Cell Structure and Function has 9%. Human Physiology has 20% weightage. Reproduction chapter has 9% and Genetics and Evolution has 18% weightage. Biology and Human Welfare has 9% weightage. Biology and its application has 4% weightage and Ecology and Environment has 6% weightage
18-20% is 15-20 questions, 12- 14% is 10 questions, 10% is 6-7 questions, 9% is 4-5 questions, 6-7% is 3 questions, 4- 5% is 2 questions , 2-3% is 1 question.
This is an observation based on previous years question papers.

So these should be your go to topics for the next 25 days. They should help you score decent.