The Earth is divided into three chemical layers: the Core [Inner Core (D) and Outer Core (C)], the Mantle (B) and the Crust (A). The Core is predominantly composed of iron and nickel. Even after 4.5 billion years of cooling, the Earth's core remains very hot.
Answer:
E = energy = ? ,
λ = Wavelength = 5.89 × 10^-7 m —> = 589 ×10 ^-9 m ,
h =Planck constant = 6.63 × 10^-34 J.s ,
f = frequency of photo/ electromagnetic radiation = c/λ ,
c = Speed of light in a vacuum = 3 × 10^8 m/s
___o___o____

I hope I helped you^_^
Each shell contains a fixed number of electrons. The general formula of the number of electrons can be hold in n-th shell is 2n². 5th shell can hold 2x5² = 50 number of electrons.
1st shell contains 2 X 1²= 2 number of electrons, 2nd shell contains 2 X 2²=8 number of electrons, 3rd shell contains 2 X 3²=18 number of electrons, 4th shell contains 2 X 4²=32 number of electrons, 5th shell contains 2 X 5²=50 number of electrons and so on.
If you go backwards two elements, you will find Neon (Ne). If you go forwards six, you will find Argon (Ar). so the closest will be neon