These are common questions. You  can read through

Common Admission Test or CAT, as commonly called, is a joined entrance exam conducted by IIMs for admission into their management courses. As per their policy of rotation every year, the exam is conducted by some different IIM. The CAT scores are accepted by IIMs and other B-School PAN-India, such as FMS-Delhi, SP Jain, JBIMS, IITs, and NITIE etc.
The CAT is a 3 hour, online test. CAT ’16 was held in December and the paper comprised of three sections:
• Verbal Ability and Reading Comprehension (VARC): 34 questions; 60 minutes
• Data Interpretation and Logical Reasoning (DII-LR): 32 questions; 60 minutes
• Quantitative ability (QA) : 34 questions; 60 minutes

As per the CAT eligibility criteria, any candidate applying for CAT must have completed or would be appearing for Bachelor’s degree, final year examination with minimum of 50% aggregate. The degree should be granted by any university incorporated or declared to be deemed under Section 3 of the UGC Act 1956 or an equivalent qualification recognized by Ministry of HRD, Government of India.

CAT eligibility for reserved categories as decided by IIMs is as follows: a) 15% of seats are kept reserved for Scheduled Caste (SC);
b) 7.5% of seats are kept reserved for Scheduled Tribe (ST);
c) 27% of seats are kept reserved for Other Backward Classes (OBC);
d) 3% of seats are kept reserved for Persons with Disability (PWD). The categories of disability include:
a) low vision blindness,
b) hearing impairment,
c) loco motor disability/cerebral palsy.
Any candidate who wishes to apply for this category will be eligible if only he/she suffers from any listed disabilities to the extent of less than 40%, as certified by a medical authority.