Question

Pure Substances
(Elements & Compounds)
Homogeneous
Mixtures (Solutions)
Heterogeneous
Mixtures
(Mechanical
Mixtures)
Copper Wire



Pizza



Lemonade



Rust (Iron Oxide)


•◎〇
Oxygen Gas



Granite Rock



Silver Ring



Baking Soda
(NaHco,)



Salt Water



Chocolate Chip
Cookie

Answer 1

Here’s a simple classification with brief notes.

Pure substances — Elements
- Copper wire (Cu) — element (metal)
- Oxygen gas (O2) — element (diatomic gas)
- Silver ring — element if pure silver (Ag); often a silver alloy (sterling) so in practice may be a mixture/alloy

Pure substances — Compounds
- Rust (iron oxide, e.g. Fe2O3) — compound (iron oxide)
- Baking soda (NaHCO3) — compound

Homogeneous mixtures (solutions)
- Salt water — solution (salt dissolved in water)
- Lemonade — usually a homogeneous solution (sugar and lemon components dissolved); may be heterogeneous if pulp/suspended solids are present

Heterogeneous mixtures (mechanical mixtures)
- Pizza — heterogeneous mixture (different components not uniformly distributed)
- Granite rock — heterogeneous mixture of minerals (e.g., quartz, feldspar, mica)
- Chocolate chip cookie — heterogeneous mixture (chips and dough are not uniformly distributed)

Notes: some real-world samples can be more complex (e.g., “rust” can include several iron oxides/hydroxides; a silver ring can be an alloy), so classification sometimes depends on the specific sample.