i also have problem with physics and chemistry...how can i handle it with atleast good marks...

Hi,
The key to approach these two subjects are to understand the basic concepts first. Talking about Chemistry first, concepts such as molarity, heat, quantitative properties of matter, electronic composition are the most basic concepts. Once you understand these, you can move onto Chemical bonding, Ionic chemistry, Inorganic chemistry, Chemical bonding and Thermodynamics. Next you should cover Organic chemistry, coordination compounds and periodic table chapters. The key is to remember important properties of elements, especially key elements. Some formulas in Thermodynamics, Basic chemistry, Atomic structures and basic structures and reactions in Organic chemistry are important to remember. Once you have covered most of the course, start on solving questions. Past year questions are super important and are often repeated in exams.
Coming to Physics, understanding concepts is the most important part. Mechanics (fluid and solid), Electromagnetism, Current and Electricity, Waves and SHM, Rotational motion, Quantum Physics are some of the most important topics and concepts are the key to securing good marks. Along with that, try to solve as many questions as you can. Study about a topic and then follow up with a good amount of questions to strengthen your concept and then move onto another topic. This way you'll also learn how to interlink two different topics. Again, solving past year papers are important.

Hope this helps. Good luck.