Chemical formulas contain subscripts. What is the purpose of a subscript?
A. It indicates the number of atoms of each element in a
chemical formula
B. It shows the most important element in each chemical
formula
C. It ranks the elements from highest to lowest mass in the
chemical formula.
D. It is used to separate letters in chemical formulas.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

i think the answer would d

its probably to later but whats the question