Could you help me to find out any free software for conducting an online exam in class room? It should be able to tell highest scorer in this exam and highest in any given subject.
did you try any of the tools suggested by Saikat and James? Please let us know whether they worked for you. Thank you!
I don't know if this is the type you are looking for, but you can check out - Safe Exam Browser.
As far as my knowledge goes, Moodle is used quite a lot to create quizzes and online exams. A complete Course Management System can be set up with Moodle.
Wondershare QuizCreator is a commercial product for creating multimedia quizzes.
I second Moodle - I used it quite extensively during my time teaching English in university, to both run online listening and multiple choice quizes and take homework electornically from students. It made the entire student management stuff so simple, but it does require a bit of effort to set up along with some technical know-how. It's not a one-click solution by far.