Valancy of an element is 8 . valnacy of an element shows the outermost shell electrons . therefore the element X have 8 electron in the outermost shell.

Valency of an Element and Electron Configuration:
The valency of an element refers to the combining capacity of an atom of that element. It determines the number of electrons an atom of that element needs to gain, lose, or share in order to achieve a stable electron configuration. The valency of an element is determined by the number of electrons in its outermost shell, also known as the valence shell.

Valence Electrons:
Valence electrons are the electrons present in the outermost shell of an atom. These electrons are involved in chemical bonding and determine the element's reactivity. The valence electrons are responsible for the formation of chemical bonds.

Determining the Valency:
To determine the valency of an element, we need to know the number of valence electrons. The number of valence electrons can be determined by the group number of the element in the periodic table.

Valency of 8:
The valency of 8 indicates that the element has 8 electrons in its outermost shell. This means that the element belongs to Group 18 (also known as the noble gases) in the periodic table. The noble gases have a fully filled outermost shell with 8 electrons, except for helium, which has 2 electrons in its outermost shell.

Explanation of the Options:
a) 6 electrons: If an element has 6 electrons in its outermost shell, it would have a valency of 6, not 8.
b) 8 electrons: An element with 8 electrons in its outermost shell has a valency of 8, which is the correct answer.
c) 7 electrons: If an element has 7 electrons in its outermost shell, it would have a valency of 7, not 8.
d) 5 electrons: If an element has 5 electrons in its outermost shell, it would have a valency of 5, not 8.

Conclusion:
In summary, the valency of an element is determined by the number of electrons in its outermost shell. An element with 8 electrons in its outermost shell has a valency of 8.