Question

An element has an electronic configuration of $2,8,7$. Its valency is

• A. $1$
• B. $7$
• C. $17$
• D. $8$

Answer 1

The correct option is A

$1$

Explanation for the correct option

(A) 1

• The combining power or the combining capacity of an element is called its valency.
• Valency is simply equal to the number of electrons gained, lost, or shared by an atom of an element to achieve the nearest noble gas configuration.
• Octet rule is followed to find out the valency. According to the octet rule, a compound is said to be stable when the outermost shell of the compound is having eight electrons.
• If the number of electrons in the outer shell is between one to four, the compound is said to have positive valency.
• For compounds with electrons four, five, six, or seven, the valency is determined by subtracting the electron from eight.
• For a given question, we will subtract seven from eight getting one.

Thus, option (A) i.e. 1 is the correct answer.