It bubbles!
The baking soda dissolves in the water
Bicarbonate of soda and baking soda are the same thing. If you are referring to baking powder, please check the provided link which explains the difference between baking soda and baking powder, and what happens if you use them together.
Not if you brush your teeth with it just don't swallow it.
nothing happens!
nothing
Nothing happens when backing soda and sand are mixed. There is no reaction.
You should not use baking soda to brush your dog's teeth. Humans may use baking soda because we know not to swallow it, but dogs will inevitably swallow some amount of it and may swallow more than is safe.
it turns into pop
it bubbles
It fizzes.
nothing really