Inorganic molecules are best described as which of the following?

• A. Not complex molecules, including water, carbon dioxide and minerals
• B. Complex carbon and hydrogen molecules
• C. Containing primarily nitrogen
• D. Formed by ribosomes

Answer: (A)

Inorganic molecules are typically simple, non-carbon–hydrogen compounds, including water, carbon dioxide and minerals. Water and CO2 are classic examples that lack the carbon–hydrogen-rich structures seen in organic molecules, and minerals are inorganic compounds often formed from elements other than carbon.

So the best description is that inorganic molecules are not complex carbon–hydrogen rich molecules. The other ideas don’t fit: complex carbon–hydrogen molecules are organic, not inorganic; molecules containing primarily nitrogen can be inorganic, but that’s not a defining feature of inorganic chemistry; and ribosomes synthesize organic biomolecules like proteins, not inorganic compounds.