those pins are connected to GROUND.
What is the purpose of connect the NC pins (85 to 93) to GROUND?
Can I connect all the NC pins together and connect a resistor between NC
junction point and GROUND?
If I leave open what is effect in the output?
The pins in question are truly no connection in the chip . Therefore, the
electrical connection does not matter at all, and they can actually be left
floating without any problem.
There is the ability that the pins can improve the heat transfer by a small
amount if they are connected to a large ground plane. This is the reason they
are "grounded", but it is for thermal considerations and not electrical.