My son has picked up some abuses from kids in his school and casually uses them in conversations. Ive tried scolding him and trying to make him understand its not right but he continues. My wife and me are worried, how do I break this habit?

first of all you should ignore it and not give much attention to the same, as then your kid will keep doing it more and more. but sometimes, while talking to your son casually, mention that some words he used are not good, and that you don't want him to say them, as both of you, the parents, don't like those words. get in touch with the teachers in school and bring this up. if some child is using abusive language, it is not good and other children will also pick it up.