Question

Which sample is a pure substance?
zinc oxide
sugar dissolved in water
pond water
soil

Answers

GPT-4o mini
Among the options provided, **zinc oxide** is a pure substance. A pure substance has a uniform and definite composition, and zinc oxide is a chemical compound that consists of only zinc and oxygen in a fixed ratio.

In contrast:
- Sugar dissolved in water is a solution, not a pure substance.
- Pond water is a mixture containing various substances, including organic matter, minerals, and microorganisms.
- Soil is also a complex mixture with various components, including minerals, organic matter, water, and air.