will a student who has passed qualifying exam in second attempt with above 70 pecent in groups eligible for writing aieee?

yes He is eligible. As per rules The minimum academic qualification for appearing in AIEEE 2012 is that the candidate must have passed in final examination of 10+2 (Class XII) or its equivalent referred to as the qualifying examination (see Appendix – IX). Those appearing in 10+2 (Class XII) final