Stirring dry yeast into a bowl of hydrogen peroxide causes bubbles to form. blowing air into a glass of milk with a straw also causes bubbles to form. one of these is a physical change, and the other is a chemical change. how could you determine which type of change is occurring in each situation?

The yeast and Hydrogen Peroxide is the chemical change, because when something is changed chemically, there is a chemical added that cannot be taken away to make it go back to it's original state. However when you're blowing bubbles in milk, no chemicals were added and it will go back to it's original state.

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