Hi Vardhaman Lodha,
When a Test Taker sees a significant score drop on Test Day, the likely factors tend to involve at least one of the following:
1) Something about your practice was unrealistic and didn't match the aspects of the Official GMAT.
2) Something about Test Day itself threw you "off" your normal performance.
If you can answer a few questions, then we can probably figure out what went wrong:
1) How long have you been studying for the GMAT?
2) What GMAT resources did you use?
3) When you took your practice CATs, did you take the ENTIRE CAT every time (including the Essay and IR sections)?
4) What time of day were you taking your CATs? What time of day was your Official GMAT?
5) How did you sleep the night before your Test?
6) How long was the ride to the Testing Center from your home?
7) What did you do during your breaks on Test Day?
8) Was there anything unexpected or surprising about Test Day or the Testing Center?
9) When are you planning to retest?
Thankfully, Business Schools don't care if you take the GMAT more than once. Also, since the GMAT is a predictable, standardized Exam, you CAN train to CRUSH it.
GMAT assassins aren't born, they're made,
Rich