In order to draw a Lewis structure, it is important to . * a. determine the atomic number of each atom in the molecule
b. add unshared pairs of electrons only around nonmetal atoms
c. determine the total number of valence electrons in each atom
d. determine the electronegativity of each atom

Iknow the answer is a but i don't know why

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.

This active feature of earth's crust in building mountain ranges as well as islands. this feature is a a) cavern. b) earthquake. c) mountain. d) volcano.