What is Boyle's temperature ? and what is relation of Boyle's temperature with Vander waal's constant?

The temperature at which non ideal gas (real gas) exhibits almost ideal behaviour for a considerable range of pressure called Boyle's.
Boyle's temperature (TB) is related to Vander Waal’s constant as follows.
                    [TB = a / Rb]
Where (a) and (b)are Vander waal's constant represent  force of attraction and Volume correction respectively. And (R) is universal gas constant

The Gases which are easily liquefied have a high Boyle's temperature, for example
                 [TB (O2) = 406 K ]
Other hand the gases which are difficult to liquefy have a low Boyle's temperature, for example.
                   [TB(He) = 23 K] 

What is the structure of Blue vitriol (CuSO4) .5H2O also represent the H-Bond with water molecules?

Number of lone pair present at central atom of I3- ion and also give hybridisation and shape of ion?

I3- is polyhalide ion it is formed due to the presence of vacant d-orbital orbital in Iodine atom. It has Sp3d3 hybridisation and linear structure.

How many maximum atoms of IF7 are present in the same plane ?

IF7​ has Sp3d3 hybridisation and pentagonal bipyramidal structure that means  five Fluorine (F)  atom and one Iodine (I) atom lies at equitorial positions and while other two Fluorine (F) atom lies at axial position .So, total atoms lies in same plane will be six (6)

What is stretching frequency of C-O bond in carbonyl Complexes?

V^co = 1/2πc√k/u

Where u= reduced mass of CO

            k =force constant of CO bond

            C= Velocity of light 

           V^CO = Stretching frequency of CO in carbonyl which increases energy to stretch CO along bond axis.

(1) Stretching frequency of CO is inversely proportional to negative oxidation state of central metal atom

(2) Extent of back bonding or back acceptance is directly proportional to negative oxidation state of central metal atom.

(3) M-C bond order is directly proportional to negative oxidation state of central metal atom

(4) C-O bond order is inversely proportional to negative oxidation state of central metal atom.

(5) d C-O bond length is directly proportional to negative oxidation state of central metal atom.

(6) Bond energy of C-O bond is inversely proportional to negative oxidation state of central metal atom