Question

the table shows the percentages of hydrocarbons that are found in a sample of crude oil.
hydrocarbons | percentage
paraffins | 30
naphthenes | 49
aromatics | 15
asphaltics | 6.0
based on the given information, what is the best classification for this sample of crude oil?
○ an element
○ a pure compound
○ a pure substance
○ a mixture

Explanation:

1. Recall definitions: An element is a pure substance with one type of atom. A pure compound has fixed composition (one type of molecule/compound). A pure substance has fixed composition (element or compound). A mixture has two or more substances (with variable composition, or multiple components).
2. Analyze the crude oil: The table shows multiple hydrocarbons (paraffins, naphthenes, aromatics, asphaltic) with different percentages. So it has multiple components (different hydrocarbons) combined, which fits the definition of a mixture. Elements and pure compounds have only one type of constituent; pure substances (element or compound) have fixed composition (not multiple components with different percentages as here).

Answer:

D. a mixture