Which two elements have the same number of valence electrons? (2 points) na and sr zr and h o and s mg and p

The correct answer is O and S.

Explanation:

Valence electrons are defined as the electrons which are present in outermost shell of an element. It is determined from the electronic configuration of an element.

From the given options:

The electronic configuration of Na:

Number of valence electrons of this element are 1.

The electronic configuration of Sr:

Number of valence electrons of this element are 2.

Hence, these two elements do not have same valence electrons.

The electronic configuration of Zr:

Number of valence electrons of this element are 2.

The electronic configuration of H:

Number of valence electrons of this element are 1.

Hence, these two elements do not have same valence electrons.

The electronic configuration of O:

Number of valence electrons of this element are 6.

The electronic configuration of S:

Number of valence electrons of this element are 6.

Hence, these two elements have same number of valence electrons.

The electronic configuration of Mg:

Number of valence electrons of this element are 2.

The electronic configuration of P:

Number of valence electrons of this element are 5.

Hence, these two elements do not have same valence electrons.

Thus, the correct answer is O and S.