Answer:
8
Explanation:
The atomic mass of an atom refers to the number of protons in the nucleus of an atom. Hence, an element with 6 valence electron mean that it has 6 electrons in its outermost shell.
The atomic Number of elements with 6 valence electrons cannot necessarily be the same, however, elements with 6 valence electrons belong to group six on the periodic table.
From the options given above, :
Atomic number of 8 :
Configuration : 2, 6
Atomic number of 10 :
Configuration : 2, 8
Atomic number of 12 :
Configuration : 2, 8, 2
Hence, only the element with atomic number of 8 has 6 valence electrons in its outer most shell, hence, the answer.
