YES you can qualify CA in first attempt work hard for your final atempt. And rank is not necessary yes you will get better oppurtunities if you have rank but in long run it doesn't matter.What matters is your knowledge and nowadys you should also have good communication skills.

Rank is given to the student who cleared both group in one sitting . It means if a student couldnot clear in ist attempt  both group . then in subsequent attempt he can be eligible for rank if he secured more than 55% marks in both group in one sitting..