Greetings, Mr. Krishnan. Your son's mock scores are around 500 and that's fairly good although there's more room for improvement. If your son's marks is around 500 then the possible range of percentile that he may acquire is 93.43 - 93.93 while possible AIR may be in the range of 99205 - 116355 (although these numbers are roughly predicted and may vary/change in the final marksheet). Now, its quite natural that in State Counselling, this ranking will be decreased.

Last year, in NEET UG 2020 State Counselling of Tamil Nadu, OC NEET Marks prescribed to be included Government Payment Quota of Private Colleges ranged between 460 - 620  (approx).

In NEET UG 2018 State Counselling of Tamil Nadu, the overall range of OC Ranks prescribed to be included Government Payment Quota of Private Colleges was around 1200 - 2500 (approx) and OC NEET Marks for the same ranged between 340 - 610 (approx).

I hope all this information is enough for you to get an idea about the matter. If you have any more query, kindly post them here.

For further details you can visit this link:

https://medicine.careers360.com/articles/neet-cutoff-tamil-nadu

To predict Rank, Percentile and List of colleges eligible for admission, you can use NEET Rank Predictor - 2021 and NEET College Predictor - 2021 .