Solid substances are normally more dense than liquid substances. However, solid ice is LESS dense than liquid water. Why is this characteristic of solid ice important for life?
a) This characteristic allows lakes to freeze solid.
b) This characteristic allows the surface water of lakes to freeze.
c) This characteristic ensures that salt water does not freeze.
d) This characteristic is not important for life.

• A. This characteristic allows lakes to freeze solid.
• B. This characteristic allows the surface water of lakes to freeze.
• C. This characteristic ensures that salt water does not freeze.
• D. This characteristic is not important for life.

Answer: (B)