15. Why does the mass on the periodic table for a particular element not equal the mass of any atom of
that element.

Mass number is always an integer. Atomic mass is never an integer number for several reasons: The atomic mass reported on a periodic table is the weighted average of all the naturally occuring isotopes. ... The mass of an atom isn't what you'd get by adding up the masses of its individual protons, neutrons and electrons.

Explanation:

d.) the average kinetic energy of the gas particles is greater in container b because its particles move faster.

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.