Dear Student,
Yes, being passed your 12th you are definitely eligibile to apply for CA foundation commonly known as CPT. For appearing for it you just need to have passed your 12th boards which you have, other than that following is the eligibility criteria for CA CPT :-

Eligibility to take CA CPT:

Candidates must have passed 10+2 examination or equivalent from a recognised institution.Applicants must be registered for the Common Proficiency Test with the Board of Studies of the Indian Chartered Accountancy of India (ICAI).Even if candidates have already registered for the Professional Course, they are eligible for appearing in this test.

So, Yes you're eligible.
Hope this might help you.

Dear student
Greetings
Candidates who wish to apply for CA CPT 2018 June examination are required tofulfill following eligibility conditions of CA CPT 2018-

Candidates must have passed in 10+2 level (Senior Secondary) qualifying examination from any national or state recognised Board of Secondary Education in India.

Candidates must have registered/switched over to Common Proficiency Course with Board of Studies of ICAI on or before June 30, 2017.

Candidates CPT registration must not have expired.

Candidates applying for CA CPT 2018 June examination must have a valid registration Id as at the time of filling application form.

Yes, you are eligible!