A0°C
B4 deg * C
C100 deg * C
D10 deg * C
Answer:
B. 4 deg * C
Read Explanation:
Water exhibits an unusual behavior known as anomalous expansion, where its density does not follow the typical pattern of increasing as temperature decreases.
Maximum Density: The density of pure water is at its highest at approximately 4 degrees Celsius (39.2 degrees Fahrenheit).
Volume Contraction and Expansion:
As water cools from higher temperatures (e.g., 100°C) down to 4°C, its volume decreases and density increases, similar to most substances.
However, as water cools further from 4°C down to 0°C (its freezing point), its volume begins to expand, and its density decreases. This is contrary to the behavior of most liquids.
Ice Formation: When water freezes at 0°C, it forms ice, which is less dense than liquid water. This is why ice floats on water. The open, crystalline structure of ice is responsible for its lower density compared to liquid water.
Hydrogen Bonding: This anomalous behavior is attributed to the extensive network of hydrogen bonds between water molecules. As temperature decreases, these bonds cause molecules to pack closer until 4°C. Below this temperature, the hydrogen bonds start to form a more ordered, less compact lattice structure, leading to expansion.
Importance in Aquatic Life: This property is crucial for aquatic ecosystems. Water at the bottom of a lake or river cools to 4°C and becomes the densest. As it cools further, it rises to the surface and freezes, forming ice that insulates the water below, preventing it from freezing solid and allowing aquatic life to survive in the colder months.