Question

The table lists the chemical formulas or symbols of a few common substances. Which two substances are compounds?

Responses
A aluminum and ironaluminum and iron
B iron and sodium chlorideiron and sodium chloride
C carbon dioxide and aluminumcarbon dioxide and aluminum
D sodium chloride and carbon dioxide

Answer 1

To determine which two substances are compounds, it's important to understand the definitions of elements and compounds:

- **Elements** are pure substances that consist of only one type of atom and cannot be broken down into simpler substances. Examples include aluminum (Al) and iron (Fe).
- **Compounds** are substances formed when two or more elements chemically bond together in fixed proportions. Examples include sodium chloride (NaCl) and carbon dioxide (CO2).

Now let's analyze the responses:

A. aluminum and iron - Both are elements.
B. iron and sodium chloride - Iron is an element, and sodium chloride is a compound.
C. carbon dioxide and aluminum - Carbon dioxide is a compound, and aluminum is an element.
D. sodium chloride and carbon dioxide - Both are compounds.

The two substances that are compounds from the given options are:

**D. sodium chloride and carbon dioxide**.