Question

The number of valence electron and the valency with respect to hydrogen are equal for:
(A) Sulphur
(B) Silicon
(C) Phosphorus
(D) Chlorine

Answer 1

Hint: Firstly, we should know the atomic number and electronic configuration of each element in option. By comparing the valence electron of hydrogen and each of the compounds of element with hydrogen, the elements that are given in the option we would be able find the answer for this question.

Complete step by step answer:
Valence electrons are the electron that is in the outermost shell of an element. The number of bonds an atom can make is known as valency of an element. The atomic number of sulphur, silicon, phosphorus and chlorine are 16, 14, 15 and 17 respectively.

Option A is sulphur, the electronic configuration of sulphur is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^4}$.The valence electron is 6. Its compound with hydrogen is ${H_2}S$. The valency of sulphur with respect to hydrogen is 2.

Option B is silicon, the electronic configuration of silicon is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^2}$. The valence electron is 4. Its compound with hydrogen is$Si{H_4}$. The valency of silicon with respect to hydrogen is 4.

Option C is phosphorus, the electronic configuration of phosphorus is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^3}$. The valence electron is 5. Its compound with hydrogen is $P{H_3}$. The valency of phosphorus with respect to hydrogen is 3.

Option D is chlorine, the electronic configuration of chlorine is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$. The valence electron is 7. Its compound with hydrogen is HCl. The valency of phosphorus with respect to hydrogen is 1.
So, the correct answer is “Option B”.

Note: The outermost electron at the first place is ready to lose or gain electrons resulting in formation of compounds with other atoms, so valence electrons are taken into account to solve this question. Carefully understands the definition of valency.