Question

Which of the following is not pseudo halogen?
A) (\[{\text{C}}{{\text{N}}_{\text{2}}}\])
B) (\[{\text{SC}}{{\text{N}}_{\text{2}}}\])
C) (\[{\text{OCN}}\])2
D) \[{{\text{H}}_{\text{2}}}\]

Answer 1

Hint: In periodic table totally 118 elements are present now. In the periodic table there are eighteen groups and seven periods. In the periodic table the seventeenth group is the halogen group. In this group, four elements are only considered as halogen out of five elements in the column. There are fluorine, chlorine, bromine and iodine considered as halogen in the modern periodic table. The symbol of \[{\text{X}}\]is used for an element that is halogen in the chemical reaction.

Complete answer:
The pseudo halogen is nothing but polyatomic molecules which resembles the halogen property in the chemical nature. The pseudo halogens are used for substitutes of halogens in the chemical reaction.
Cyanide, cyanate and thiocyanate are considered pseudo halogen.
Hydrogen molecules are not considered as pseudo halogen because the electronegativity is low.
Acceding to the above discussion, we conclude\[{\text{C}}{{\text{N}}_{\text{2}}}\],\[{\text{SC}}{{\text{N}}_{\text{2}}}\], (\[{\text{OCN}}\])2 are pseudo halogen and \[{{\text{H}}_{\text{2}}}\]is not pseudo halogen.

Hence, option D is correct, because \[{{\text{H}}_{\text{2}}}\] is not pseudo halogen.

Note:
We have to know that the symbol of \[{\text{X}}\] is used for an element, there are fluorine, chlorine, iodine and bromine in the chemical reaction. Halogen is the most electron affinity group in the periodic table. Halogen is also the most electronegativity group in the periodic table. The ionisation energy of the halogen is very less compared to other groups. In halogen from top to bottom, electron affinity decreases. Chlorine is the highest electron affinity species in the periodic table, because the size of the fluorine is very small compared to chlorine. But, the electronegativity value of fluorine is high compared to the electronegativity value of chlorine.