This is not the year to have second thoughts. trust me science is a challenging n intersting subject.well i can only suggest you a simple solution.

Be attentive in class, make it a habit to put in dedicated efforts every day to keep abreast of topics taught in class. Start enjoying the subject & wen u do that u really don hav to study.

cant assure a 90 ul hav to be satisfied wit wat ev u get, noothn comes easy, no pains no gains.

The only way to do better is to study. Take notes on your study, develop mnemonic devices to remember things, and generally learn the subject. Do’nt listen to music, Don’t watch TV Don’t study with friends who do not want the same things you do – higher grades.