Question

formaldehyde has a wide range of uses, many of them in manufacturing. its chemical formula is ch₂o. the model below represents formaldehyde. based on the model, which statement best describes formaldehyde molecules?
a. formaldehyde molecules do not form a repeating pattern and cannot freely move past each other
b. formaldehyde molecules do not form an extended structure and can freely move past each other.
c. formaldehyde molecules form a repeating pattern and can freely move past each other.
d. formaldehyde molecules form an extended structure and cannot freely move past each other.

Explanation:

1. Recall the properties of molecular substances (like formaldehyde, a covalent molecular compound) vs. extended structures (like ionic or metallic solids, or network covalent solids).
2. Molecular substances: Molecules are discrete (no extended repeating structure) and in the liquid or gas phase (or sometimes solid with weak forces), molecules can move past each other.
3. Analyze options:

• Option A: Says they can’t move past each other – incorrect, as molecular substances (if liquid/gas) can move.
• Option B: Molecules don’t form extended structure (correct, since formaldehyde is molecular, not ionic/network) and can move past each other (correct for molecular in fluid states).
• Option C: Says they form a repeating pattern – incorrect, molecular substances have discrete molecules, not extended repeating patterns.
• Option D: Says they form extended structure and can’t move – both incorrect.

Answer:

B. Formaldehyde molecules do not form an extended structure and can freely move past each other.