7. Although carbon's three isotopes are carbon-12, carbon-13, and carbon-14, its average atomic mass is 12.01 because

A. carbon-12 is the heaviest isotope.

B. carbon-12 is most useful to humans.

C. carbon-12 is the most common isotope.

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.

space exploration has led to the development and technological improvement of many everyday items. (if this answer is wrong i will find the right answer) : )

може ли да зареждате повече информация, моля