Answer to Question 1
C
Answer to Question 2
Most substances increase their density as temperatures decrease. This is the case for liquid water, but only until it reaches approximately 4C (or 39F). Below this temperature, water begins to decrease its density and expands by about 9 during the transition from liquid to solid state at the freezing point. Ice is less dense than water, so it floats.
The fact that ice floats is important in high latitudes. Not only does it give a surface for polar bears and other Arctic organisms to live on, it helps to insulate the ocean beneath from the extremely cold atmospheric temperatures. This allows the water to remain in a liquid form and be able to support the diversity of life that exists under the ice at high latitudes.
The open ocean is the most extensive biome on earth.
"Visual Acuity Testing, Assessing Distance Vision
The Sun as it appears from the surface of the Earth at Sunset.
Moon and Earth
Earth’s Revolution
Earth Atmosphere