Answer:
1. The core electrons are 10 
 
2. The valence electrons are 8 
Explaination:
Core electrons are electrons located in the inner shells of and atom. 
 
Valence electrons are electrons located on the outermost shell of an atom 
 
From the question given above, we obtained: 
 
Ar (18) => [Ne] 3s²3p⁶ 
 
Recall 
 
Ne (10) => 1s² 2s²2p⁶ 
Therefore, 
 
Ar (18) => [1s² 2s²2p⁶] 3s²3p⁶ 
 
From the above illustration, 
 
Inner shell (core shell) => 1s² 2s²2p⁶ 
Outermost shell (valence shell) => 3s²3p⁶ 
1. Determination of the core electrons 
Inner shell (core shell) => 1s² 2s²2p⁶ 
 
Core electrons = 2 + 2 + 6 
 
Core electrons = 10 
2. Determination of the valence electrons 
Outermost shell (valence shell) => 3s²3p⁶ 
 
Valence electron = 2 + 6 
 
Valence electron = 8