How many moles are there in 3.92x 10^20 atoms of beryllium

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.

Avariable that is not being directly tested during an experiment should be

Air can be considered a mixture. which statement does not explain why?