Question

why should the water in the water bowl or large beaker be replaced after each reaction ​

Answer 1

Explanation:

Water is almost incompressible. Get a pump for pumping bicyle tyres, put your finger over the end and push the handle down. The air inside compresses, let go and the handle springs back out. Now try this with water- the handle won’t compress the water. Another example would be diving into water and doing a belly flop. The water does not compress like a matress used for high jumps/pole vaults. It hurts.

So the water won’t compress, its volume will not reduce and it is in a beaker. When the stone is placed in the beaker, the water has to take up space somewhere else or be compressed. The water cannot move downwards or sideways because it is in a beaker, so it moves the only way it can - upwards.