classify the materials based on their composition. utensils wood aluminum foil glass milk plastic water air…

Explanation:

Step1: Define substance

A substance has a fixed - composition.

Step2: Define homogeneous mixture

A homogeneous mixture has uniform composition throughout.

Step3: Define heterogeneous mixture

A heterogeneous mixture has non - uniform composition.

Step4: Classify utensils

Utensils (usually made of metal) are substances as they have a definite chemical composition.

Step5: Classify wood

Wood is a heterogeneous mixture as it has different components like fibers, sap, etc. with non - uniform distribution.

Step6: Classify aluminum foil

Aluminum foil is a substance as it is mainly aluminum with a definite composition.

Step7: Classify glass

Glass is a substance as it has a relatively fixed chemical composition of silica and other additives.

Step8: Classify milk

Milk is a heterogeneous mixture as it contains fat globules, proteins, and water which are not uniformly distributed.

Step9: Classify plastic

Plastic is a substance as it is a polymer with a defined chemical structure.

Step10: Classify water

Pure water is a substance as it has a fixed chemical formula ($H_2O$).

Step11: Classify air

Air is a homogeneous mixture as it contains nitrogen, oxygen, carbon - dioxide etc. uniformly distributed.

Answer:

Utensils: substance Wood: heterogeneous mixture Aluminum foil: substance Glass: substance Milk: heterogeneous mixture Plastic: substance Water: substance Air: homogeneous mixture