salt and pepper water and sugar iron nails and pennies baking soda and vinegar
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Materials combine chemically or physically. Which materials form a new substance when chemically combined?
Possibilities:
- salt and pepper
- water and sugar
- iron nails and pennies
- baking soda and vinegar

baking soda and vinegar