2. The diagram below represents the bright-line spectra of four elements and a bright-line spectrum
produced by a mixture of two of these elements.
Which two elements are in this mixture?
(1) barium and hydrogen
(2) barium and lithium
(3) helium and hydrogen
(4) helium and lithium

A2-kg bowling ball is 1 meter off the ground on a post when it falls. just before it reaches the ground,its traveling 4.4 m/s. assuming that there is no air resistant, which statement is true a. the initial potential energy is less then the final kinetic energy b. the mechanical energy is not conserved c. the mechanical energy is conserved d. the initial potential energy is greater than the final kinetic energy