Yes ,  PCM students are  eligible to became CA.
For this you have to prepare very well as it has lots of crowd because leaving physics and chemistry and adapting tax , law , financing etc. Won't be easy.

CA exam has 3 levels i.e. CPT , IPCC and FINAL.
There are 2 routes for this
1. Foundation route - appear after 12th , study for 4 months , fill the application form and appear for exam.
2. Direct entry route - apply after graduation , register for exams if cleared intermediate level you are eligible for 2nd level.