Which of these pairs of elements have the same number of valence electrons?

a) hydrogen and helium

b) sodium and potassium

c) carbon and oxygen

d) boron and beryllium

Answer : The correct option is, (B) sodium and potassium

Explanation :

Valence electrons : Valence electrons are those electrons which are present in the outermost shell of the element.

As we know that,

Option (A) :

Element = Hydrogen

Atomic number = Number of electrons = 1

The electronic configuration is,

The number of valence electrons = 1

Element = Helium

Atomic number = Number of electrons = 2

The electronic configuration is,

The number of valence electrons = 2

Option (B) :

Element = Sodium

Atomic number = Number of electrons = 11

The electronic configuration is,

The number of valence electrons = 1

Element = Potassium

Atomic number = Number of electrons = 19

The electronic configuration is,

The number of valence electrons = 1

Option (C) :

Element = Carbon

Atomic number = Number of electrons = 6

The electronic configuration is,

The number of valence electrons = 4

Element = Oxygen

Atomic number = Number of electrons = 8

The electronic configuration is,

The number of valence electrons = 6

Option (D) :

Element = Boron

Atomic number = Number of electrons = 5

The electronic configuration is,

The number of valence electrons = 3

Element = Beryllium

Atomic number = Number of electrons = 4

The electronic configuration is,

The number of valence electrons = 2

From this we conclude that, the sodium and potassium are the elements have the same number of valence electrons.

Hence, the correct option is, (B)

answer

i think the answer is a) as air pressure in an area increases, the density of the gas particles in that area decreases.

hope it

the electron configuration that you gave me has 16 electrons ergo it has 16 protons ergo it is the element sulfur.