What does a metreologist study

What is the equilibrium constant of aa+bb=cc+dd

Me i dont know what to do! the table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.

What type of electromagnetic waves does the human eye see as the colors red blue or green a visible light waves b radio waves c infrared waves d microwaves