1. Which of the following common materials is best described as having an extended structure?
- A. A diamond
- B. A water droplet
- C. A puff of carbon dioxide
- D. A molecule of methane
2. What fundamental characteristic is shared by both simple molecules like water and extended structures like salt?
- A. They are both always solid at room temperature.
- B. They are both formed from only one type of element.
- C. They are both defined by a repeating atomic unit.
- D. They both dissolve easily in all liquids.
3. A student observes a computer model of a substance showing atoms bonded in a vast, orderly, and continuous three-dimensional lattice. How would this material be classified?
- A. As a collection of simple molecules
- B. As an extended structure
- C. As a mixture of different elements
- D. As a gaseous substance
4. Why is a single particle of oxygen gas (O₂) considered a molecule rather than an extended structure?
- A. Because it is a gas at room temperature.
- B. Because it contains more than one atom.
- C. Because it is a small, self-contained group of atoms.
- D. Because its atoms are not connected by chemical bonds.
5. If a substance is described as being composed of molecules, what does this imply about its atomic-level structure?
- A. It is made of small, discrete atomic groups.
- B. Its atoms are arranged in a massive, repeating 3D crystal lattice.
- C. It must be a solid substance with a very high melting point.
- D. It is formed from a single type of atom, making it an element.
6. What is the fundamental particle that serves as the building block for all matter?
- A. Molecules
- B. Atoms
- C. Elements
- D. Cells
7. What is the primary reason why copper is a reddish, conductive metal while sulfur is a yellow, brittle nonmetal?
- A. Copper is heavier than sulfur, which gives it different properties.
- B. They are composed of different types of atoms.
- C. The way the materials were processed and manufactured determines all of their final physical characteristics.
- D. Copper is mined from deep underground, while sulfur is found near the surface.
8. A chemist analyzes a sample of pure aluminum and a sample of pure lead. She finds they have different densities and melting points. What is the basic scientific explanation for this difference?
- A. The lead atoms are different from the aluminum atoms.
- B. The aluminum sample was shinier and therefore less dense.
- C. One sample must have been contaminated during the experiment.
- D. The samples were tested on different days under slightly different lab conditions.
9. Scientists know that gold is a soft, shiny metal and that helium is a very light, non-reactive gas. Based on this information, what is a guaranteed difference between them at the atomic level?
- A. The atoms in gold are solid particles while the atoms in helium are gaseous particles.
- B. There are more atoms in a sample of gold than in a sample of helium.
- C. They are made of different types of atoms.
- D. Gold atoms are yellow and helium atoms are clear.
10. The statement that atoms are "too small to see" implies that...
- A. everyday objects consist of a vast quantity of these particles.
- B. atoms are less important than the objects they make up.
- C. atoms only exist in scientific theories and not in the real world.
- D. only microscopic organisms are made of atoms.