Question

determine the valency of an element x whose atomic number is 15​

Answer 1

$\huge\red{HEYA\:MATE}$...

AN ELEMENT HAVING ITS ATOMIC NUMBER 15....IS PHOSPHORUS.....

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THUS IT'S VALENCY IS "3"

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HOPE IT WILL HELP YOU.....

Answer 2

It is given that X is an element.

Its atomic number is 15.

Its electronic configuration is 2, 8, 5, that is, it has 5 electrons in its outermost shell or orbit

In order to complete its octate, the element X needs to accept 3 electrons.

So, the valency of the element X is 3 or it can be said that X is a tetravalent element.