I have only done 14 chapters out of 19 in quantitative. So is it possible to score good marks in quantitative? ?

Yes it is still possible for you to score good marks in quantitative if your basics are strong in the syllabus you have covered. Make sure whatever you have studied your basics are very strong then only you will be able to attempt tricky questions with good speed and accuracy. I will recommend instead of giving lot of time on the remaining chapters you can atleast see the basics of those chapters.

Now as less than a month time is left for CAT exam so you need to brush up on all the basics of 3 sections and start giving lots of online mock test and analyse the solutions of each mock test which will help you in overcoming your mistakes and come up with a strategy to attempt your paper which will definitely help you in improving your marks and percentile. It will also help you in knowing your strength and weakness which will help you in attempting easy questions first that will help you in reducing the chance of errors and missing an easy question and also will give you enough time to attempt medium level questions so this will help you to improve speed and accuracy leading to increase in percentile.

Work hard you can definitely score well in quantitative section and attain a good percentile.
All the best for your preparations and exams!!