How is a compound different from a mixture?

a. it is made of one substance
b. it can not be made of organic materials
c. it cannot be broken down.
d. it can not be seperated by a physical change.

D.It can not be separated by a physical change.

why is arctic sea ice important? arctic sea ice keeps the polar regions cool and moderate global climate. sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. as sea ice melts in the summer, it exposes the dark ocean surface.