Which of the following liquids has the highest density at room temperature?

• A. Water (H_2O)
• B. Ethanol (C_2H_5OH)
• C. Mercury (Hg)
• D. Glycerol (C_3H_8O_3)

Answer: (C)

Verified step by step guidance

1. Understand that density is defined as mass per unit volume, given by the formula \(\text{density} = \frac{\text{mass}}{\text{volume}}\).
2. Recall that density depends on both the molar mass of the substance and how closely its molecules are packed in the liquid state.
3. Consider the molecular weights and intermolecular forces of each liquid: Water (H_2O), Ethanol (C_2H_5OH), Glycerol (C_3H_8O_3), and Mercury (Hg), noting that mercury is a metal and exists as a dense liquid at room temperature.
4. Recognize that metals like mercury have atoms packed very tightly, resulting in much higher density compared to molecular liquids like water, ethanol, and glycerol.
5. Conclude that among the given options, mercury has the highest density at room temperature due to its atomic structure and metallic bonding, which leads to a much greater mass per unit volume.