Final answer:
Among the options provided, oxygen is the only pure substance as it is an element with a distinct chemical composition. All the other options, such as air, salt water and maple syrup, are mixtures.
Step-by-step explanation:
The question is asking to identify pure substances from the given options. A pure substance is either an element or a compound that has a fixed chemical composition and distinct properties. Among the given options, oxygen (a) is an element and therefore a pure substance. Air (e) is a homogeneous mixture, not a pure substance. Salt water is also considered a homogeneous mixture or solution, as it is a combination of water and salt. Maple syrup is also a mixture consisting of various sugars and other compounds. For further clarity on the matter:
- Oxygen (an element and a pure substance)
- Air (a mixture of nitrogen, oxygen, and other gases)
- Salt water (a homogeneous mixture of salt dissolved in water)
- Maple syrup (a complex mixture)