Answer: Chlorine and manganese have seven valence electrons.
Explanation:
Valence electrons are defined as the electrons which are present in outermost shell of an element. It is determined by the electronic configuration of an element.
For the given options:
Option 1: Chlorine (Cl)
The atomic number of this element is 17.
Electronic configuration of Cl: [tex][Ne]3s^23p^5[/tex]
This element has 7 electrons in the outermost shell and thus it has 7 valence electrons.
Option 2: Nitrogen (N)
The atomic number of this element is 7.
Electronic configuration of N: [tex][He]2s^22p^3[/tex]
This element has 5 electrons in the outermost shell and thus it has 5 valence electrons.
Option 3: Manganese (Mn)
The atomic number of this element is 25.
Electronic configuration of Mn: [tex][Ar]4s^23d^5[/tex]
In transition elements, the number of ns and (n-1) d electrons are considered as valence electrons. Thus, it has 7 valence electrons.
Option 4: Oxygen (O)
The atomic number of this element is 8.
Electronic configuration of O: [tex][He]2s^22p^4[/tex]
This element has 6 electrons in the outermost shell and thus it has 6 valence electrons.
From the above information, chlorine and manganese have seven valence electrons.
