An electron in a calcium atom gains enough energy to move from the first shell to the second shell, the calcium atom becomes A. a negative ion
B. a positive ion
C. an atom in an exited state
D. an atom in the ground State

Which function is performed by earths atmosphere? a. ultraviolet rays are prevented from reaching the ozone layer. b. earths temperature is raised and moderated by trapping in heat c. charged particles from the sun are prevented from reaching earth. d. magnetic charges from space are prevented from reaching earths surface.

In numbering carbon atoms in the parent chain of a hydrocarbon, why would you number from right to left, rather than left to right

What happened to the amount of carbon dioxide in the atmosphere from 2010–2017?