Question

This question has two parts.

Part A

The table below lists elements and compounds.


Elements Compounds
Ne

H2O
Na NaCl
Pb ?

Which of the following substances belongs in the column listing examples of compounds?

Select {responseValue}
Cu

Select {responseValue}
NH3

Select {responseValue}
Ag

Select {responseValue}
He

Part B

Which statement best explains the answer to Part A?

Select {responseValue}
Chemical formulas for compounds contain two or more of the same types of atoms.

Select {responseValue}
The chemical formula for a molecule must include two or more different kinds of atoms.

Select {responseValue}
Chemical formulas for compounds contain two or more different types of atoms.

Select {responseValue}
An element would have two or more different types of atoms combined in its formula.

...

Answer 1

### Part A

The substance that belongs in the column listing examples of compounds is: **NH3**

### Part B

The statement that best explains the answer to Part A is: **Chemical formulas for compounds contain two or more different types of atoms.**

### Explanation
- **NH3** (ammonia) is a compound made of nitrogen (N) and hydrogen (H) atoms, which are different types of atoms.
- **Cu** (copper), **Ag** (silver), and **He** (helium) are elements and consist of only one type of atom, which is why they are not classified as compounds.