Atoms emit visible and ultraviolet light asthey are:. a. heated and the solid melts to form a liquid
b. the atoms condense from a gas to a liquid
c. the electrons move about the atom within an orbit
d. electrons jump from lower energy levels to higher levels
e. electrons jump from higher energy levels to lower levels

Use the periodic table to determine the electron configuration of dysprosium (dy) and americium (am) in noble-gas notation.

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next

Arectangle has a diagonal 20 inches long that forms angles of 60 and 30 with the sides. find the perimeter of the rectangle. for geometry