Which of the following substances has the greatest density?

• A. Aluminum (Al)
• B. Gold (Au)
• C. Ethanol (C_2H_5OH)
• D. Water (H_2O)

Answer: (B)

Verified step by step guidance

1. Recall that density is defined as mass per unit volume, given by the formula \(\text{density} = \frac{\text{mass}}{\text{volume}}\).
2. Understand that density depends on how closely packed the atoms or molecules are in a substance, which varies between solids, liquids, and gases.
3. Identify the physical states of the substances: Aluminum (Al) and Gold (Au) are metals (solids), while Ethanol (\(C_2H_5OH\)) and Water (\(H_2O\)) are liquids under standard conditions.
4. Recognize that metals generally have higher densities than liquids because their atoms are packed more tightly in a solid lattice structure.
5. Compare typical density values of these substances (from reference data or periodic table): Gold has a notably high density compared to Aluminum, Ethanol, and Water, which explains why Gold has the greatest density among the options.