Hi veeralshah,
You're essentially asking about how the GMAT scoring algorithm "works" - it's actually far more complicated than most people realize. It takes into account a number of different factors, including the relative difficulty of the question, whether you were expected to get it correct or not, the placement of the question, what's going on "around it", the "strings" of correct and incorrect answers, whether the question even counts or not (some questions are "experimental" and are worth 0), if you leave questions unanswered and incur a penalty, etc. As such, you shouldn't be spending time trying to figure it all out. You'd be better served working on building up your skills.
In the broader sense, you should focus on NOT making silly/little mistakes. Whether you face those issues in the first 5 questions or at the end of a section, making too many little mistakes on "gettable" questions will keep you from hitting your score goals.
How long have you been studying?
When are you planning to take the GMAT?
GMAT assassins aren't born, they're made,
Rich