Hello,

First of all I would appreciate that you on choose to become an IAS officer.

Coming to your question, Yes you can join for arts even after completing your 12th in Science. You need to score really well(more than 85%) to get admission into some of the best ARTs colleges in India.

Below I have mentioned some of the best ART colleges in India:

1. Lady Shri Ram College for Women, Delhi
2. Loyola College, Chennai
3. St. Stephen's College, Delhi
4. St.Xavier's College, Mumbai
5. St.Xavier's College, Kolkata
6. Presidency College, Kolkata
7. Fergusson College, Pune
8. Christ College, Bangalore
9. Stella Maris College, Chennai
10. Miranda House, Delhi
11. St.Xavier's College, Ahmedabad
12. Presidency College, Kolkata
13. Symbiosis Society's College, Pune
14. Hindu College, Delhi
15. Mount Carmel College, Bangalore
16. St. Joseph's College, Bangalore
17. Madras Christian College, Chennai
18. Sri Venkateswara College, Delhi
19. Sophia College for Women, Mumbai
20. Hansraj College, Delhi
21. K.J Somaiya College of Arts and Commerce, Mumbai
22. Jesus and Mary College, Delhi
23. Ramjas College, Delhi
24. St. Teresa College, Cochin
25. Mithibai College of Arts, Mumbai

Hope this helps.

Good Luck