CAT

Good CAT scores vary depending on the competitiveness of the IIMs you wish to attend. However, based on what we know about business school admissions in India and percentile-to-mark conversion, we can infer what a good score might be.
(If you're uncertain about the tier of the IIM you wish to attend, you can find the brief summary of Indian business school tiers here). Top-Tier Schools: Above 200, with the sectional score between 80 and 85 (possibly lower in data interpretation and logical reasoning). Second-Tier Schools: Above 120, with sectional scores in the 40s and 50s (possibly lower in data interpretation and logical reasoning).
Third-Tier Schools: Above 100, with sectional scores in the 30s and 40s (possibly lower in Data Interpretation and Logical Reasoning). Even if you haven't achieved these marks on the CAT though, remember that different schools weight the importance of the CAT differently. Furthermore, other factors, including your employment history and school record, can be equally or more important.

You are eligible to appear for CAT in final year of B.Com. Below mentioned is the CAT eligibility criteria for the students appearing graduation degree:
Candidates appearing for the final year of Bachelors degree/ equivalent qualification examination and those who have completed degree requirements and are awaiting results can also apply. However, it may be noted that such candidates, if selected, will be allowed to join the programme provisionally, only if they submit a certificate from the Principal/ Registrar of their university/ institution stating that they have completed all the requirements for obtaining the Bachelors degree/ equivalent qualification on the date of the issue of the certificate.