Q: Does having a backlog in 2nd year B.Com effect my eligibility for IAS preliminary exams?

you can apply for IAS while you have backlog in your 2nd year. but you have to clear all the your backlogs in final year of your B.Com. it does not effect your eligibility in IAS. you can definitely apply for IAS. for IAS you just need to complete or studying in final year of graduation in any discipline with any percentage. \
IAS stands for Indian Administration Service. for IAS you have to write Civil Services exam that is conducted by UPSC every year. IAS is one of the powerful post. 

Civil Services exam conducted in three stages:1. CSAT(Prelims)
2. Mains
3. Interview

for Civil Services your age must be within 21 years to 30 years on 1 August of the year of exam. there is relaxation in upper age limit up to 3 years for OBC and 5 years for SC/ST candidates.


Important dates of Civil Services exam in 2014:

CSAT(Prelims):
date of Notification: 17.05.2014
last date of receipt of application: 16.06.2014
date of exam: 24.08.2014 


Mains:
date of exam: 14.12.2014

you have to apply for the exam online on given link:

http://upsconline.nic.in/