How can an electron in an atom lose energy to go from a higher ...

[mckennatimberlake]

How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
 
  A) It absorbs a photon equal in energy to its own energy drop.
  B) It loses kinetic energy.
  C) It loses gravitational potential energy.
  D) It releases a photon equal in energy to its own energy drop.
  E) It exchanges gravitational potential energy for kinetic energy.

Question 2

Which of the following is not consistent with observations of the cosmic microwave background?
 
  A) The universe is at least 20 billion years old.
  B) The universe is geometrically flat (in the four dimensions of spacetime).
  C) Dark energy, whatever it is, represents the majority of the energy content of the universe.
  D) The matter density (both luminous and dark matter combined) in the universe is only about one-fourth of the critical density.

[akudia]

Answer to Question 1

D

Answer to Question 2

A

[mckennatimberlake]

TYSM

[xiaomengxian]

Gracias!