Question

why does a baloon burst when placed on the openning of a soda bottle? thank you.

Answer 1

What is being emitted from the soda? A gas, perhaps? Perhaps CO2. Is that the gas dissolved in soft drinks? I don't think a balloon will burst if placed over the opening of an empty soda bottle so I assume you intended to write your question to reflect that the bottle had soda in it (and fresh, not flat, soda at that).