Question

multiple choice 10 points
why does ice float on water?
ice and water have the same density.
ice is less dense than water and expands when it freezes.
ice has a lower specific heat index.
ice is denser than water and compacts when it freezes.
multiple choice 10 points
why is water considered a polar molecule?
it has a positive charge on both the hydrogen (h) and oxygen (o) sides.
it has a positive charge on the hydrogen (h) side and a negative charge on the oxygen (o) side.
it has a positive charge on the oxygen (o) side.
it has an equal distribution of charges.
it has a negative charge on both sides hydrogen (h) and oxygen (o) sides.

Explanation:

• For the question "Why is water considered a polar molecule?":
• A polar molecule has regions of positive and negative charge. In a water molecule (\(H_2O\)), oxygen is more electronegative than hydrogen. So, the oxygen atom pulls the shared electrons closer to itself, creating a partial negative charge (\(\delta -\)) on the oxygen side and partial positive charges (\(\delta+\)) on the hydrogen sides.
• For the question "Why does ice float on water?":
• When water freezes to form ice, the water molecules arrange themselves in a hexagonal lattice structure due to hydrogen - bonding. This structure creates more open space between the molecules compared to liquid water. Since density (\(

ho=\frac{m}{V}\), where \(m\) is mass and \(V\) is volume) is mass per unit volume, and the volume of ice is larger than the volume of the same mass of liquid water, ice has a lower density (\(
ho_{ice}<
ho_{water}\)). According to Archimedes' principle, an object with a lower density than the fluid it is placed in will float.

Answer:

• For "Why is water considered a polar molecule?": It has a positive charge on the Hydrogen (H) side and a negative charge on the Oxygen (O) side.
• For "Why does ice float on water?": Ice is less dense than water and expands when it freezes.