6.5 C Elements and Compounds

Some students are using samples of different substances for a lab investigation. They plan to observe the physical properties of each substance and record their observations in a table like the one shown.

Which of the substances observed are elements?

• S, Fe, O₂, Sr, and Al

• S, O₂, and LiF

• N₂, O₄, O₂, and LiF

• N₂O₄, Fe, Sr, and Al

In the chemical reaction shown, the products are best classified as -

• two elements

• one element and one compound

• two compounds

• two compounds and one element

The chemical equation shown represents a reaction that produces fuel for certain cars.

Which substance represented in this equation is classified as an element?

• CO

• H₂O

• CO₂

• H₂