What is the frequency of light having a wavelength of 455nm

Iknow #2 is d. i just need to know why

Which is a difference between molecular compounds and ionic compounds? select the correct answer below: question 5 options: molecular compounds typically form between a metal and a nonmetal, while ionic compounds typically form between nonmetals. molecular compounds result from the transfer of electrons between atoms to form ions, while ionic compounds result from the sharing of electrons between neutral atoms. molecular compounds are formed of discrete, neutral molecules, while ionic compounds are formed of large repeating arrays of opposite charges. molecular compounds have high melting points and high boiling points, while ionic

What type of reaction is shown below? check all that apply. 2h2o2 → 2h2o + o2 synthesis decomposition combustion