Which of these pairs of elements have the same number of valence electrons? phosphorus (p) and chlorine (cl) berylium (be) and calcium (ca) chlorine (cl) and helium (he) oxygen (o) and carbon (c)

Option (b) is the correct answer.

Explanation:

It is known that elements of same group tend to possess same number of valence electrons. As a result, they show same chemical properties.

Phosphorous (P) and chlorine (Cl) belongs to third period. Valence electrons of phosphorous are 5 and chlorine has 7 valence electrons.

Beryllium (Be) and Calcium (Ca) are group 2 elements and both of them have two valence electrons.

Helium (He) is a noble gas and it does not have any valence electrons.

Oxygen (O) has six valence electrons and carbon (C) has 4 valence electrons.

Therefore, we can conclude that berylium (Be) and calcium (Ca) is the pairs of elements have the same number of valence electrons.