It depends what it interacts with but it makes bubbles for a chemical or physical change happening to it
Salad bowls aren't completely mixed in like your still have individual uniqe parts that make up the overall product (tomatoe, onions, lettuce, etc.)
examples :
the general population could be an example (chinese, european, african-american)
urban cities also are all unique with all the different types of cars/transportation it contains
A i think sorry if it's wrong