Sulfur (S), oxygen (O2), water (H2O), and sodium chloride (NaCl) are all examples of pure substances. Which of the following describes all pure substances?

i. A pure substance consists of only one type of element..
ii. A pure substance has a definite chemical composition..
iii. A pure substance cannot be broken down into simpler substances..
iv. A pure substance is normally found as a solid at room temperature..
ii.