An element occurs as a mixture of isotopes. the atomic mass of an element is based upon

no. of protons + no. of neutrons in the neucleous

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.

the answer is b. dilution