It holds more weight in the regular water.
Your blood runs through your blood stream, every vein in your body. without that heartbeat the blood would not make it to the required places it needs to run to and you will lose oxygen and parts of your body and organs will shut down.
Most of the momentum is transferred to the ball on top. Since the collision in this situation is elastic, momentum is conserved, meaning the momentum of both balls before hitting the floor is equal to the momentum of both balls right after the collision.
1kg = 1000000000 micrograms
I hope it helps you ;)