Answer: Water at 4°C is densest; ice has open hydrogen-bonded lattice making it less dense than liquid water.
- A Water at 4°C is densest; ice has open hydrogen-bonded lattice making it less dense than liquid water
- B Solid ice molecules acquire a higher effective molecular weight than liquid water molecules under most conditions encountered
- C Liquid water expands mainly very slightly in volume as it approaches 0°C as frequently observed in practice
- D Ice is held together largely by weak van der Waals forces rather than hydrogen bonds in many documented cases
Correct answer: A. Water at 4°C is densest; ice has open hydrogen-bonded lattice making it less dense than liquid water
Explanation: In ice, hydrogen bonds create an open tetrahedral lattice with more space between molecules than in liquid water, making ice less dense.
Each water molecule's O-H bonds (covalent, solid) can hydrogen-bond (dashed) to neighbouring molecules, forming an extended network responsible for water's unusually high boiling point and density anomaly.
Concept context
The simplest and most abundant element in the universe. Study its unique position in the periodic table, isotopes (protium, deuterium, tritium), properties of water and hydrogen peroxide, and industrial uses.