Explain how the percentages of nitrogen, oxygen and carbon dioxide in the earths atmosphere today have changed from the earths early atmosphere

Which statement best describes the relationship between period and frequency of light waves? a) in wave b the period increases and the frequency decreases from wave a. b) in wave a the period increases and the frequency decreases from wave b. c) in wave b the period is shorter and the frequency is greater than in wave a. d) in wave a the period is shorter and the frequency is greater than in wave b.

In the particles are arranged in a regular, repeating pattern. a)a crystalline liquid b)a crystalline solid c)all gases d)all solids

What is the atomic mass of an atom that has 6 protons, 6 neutrons, and 6 electrons? a) 6 b) 8 c) + 1 d) 12 e) 18