Answer:
The correct answer is 5s
Explanation:
Strontium atomic number = 38
Electronic configuration is 
As 
orbital is valence orbital in strontium, the outer electrons exists in that orbital only.
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Answer: D
Explanation: It's not scientific. branlist plz
Noble Gas Cores have following electronic configuration
He = 1s²
Ne = [He] 2s², 2p⁶
Ar = [Ne] 3s², 3p⁶
Kr = [Ar] 4s², 4p⁶
Xe = [Kr] 5s², 5p⁶
Now solving for question elements,
Germanium = Ge = [Ar] 3d¹⁰, 4s², 4p²
Nickle = Ni = [Ar] 3d¹⁰, 4s²
Tunsten = W = [Xe] 4f¹⁴, 5d⁴, 6s²
Titanium = Ti = [Ar] 3d², 4s²
Iron = Fe = [Ar] 3d⁶, 4s²
Zinc = Zn = [Ar] 3d¹⁰, 4s²
