Question

why are the blueberry and strawberry pancakes considered a heterogeneous mixture? because they contain pure substances only because their ingredients are evenly mixed together because they are made of elements found on the periodic table of elements because each bite can contain a different combination of ingredients

Explanation:

A heterogeneous mixture has components that are not uniformly distributed. Pancakes with blueberries and strawberries have visible chunks of fruit. Each bite can have a different amount of fruit (different combination of ingredients). A pure substance has only one type of particle. If ingredients were evenly mixed (homogeneous), you couldn't see distinct fruit pieces. Being made of elements from the periodic table doesn't relate to mixture type.

Answer:

because each bite can contain a different combination of ingredients