Abhisek. Try to be independent. Can't you do some research by yourself. Pleading help in every matter in sajha doesn't solve your problem. You need to grow up. Why don't you use your time to find some books or websites related to that topic instead of writing in sajha. I have seen these problem in sajha from long time. people are asking help for whole chemistry problem, some are having problem with calculus. Yes sajha helps a lot but its not beneficial for you. This is not a lecture but you guys/girls need to be an independent.