Answer:
1.
Explanation:
Hello.
In this case, since both sodium and potassium are in the same group, IA, and sodium is the 11th element in the periodic table so its atomic number or number of both protons and electrons is 11 and potassium is the 19th element in the periodic table so its atomic number or number of both protons and electrons is 19 we can infer they both have 1 valence electron due to their electron configuration as shown below:
[tex]Na^{11}:1s^2,2s^2,2p^6,3s^1\\\\K^{19}:1s^2,2s^2,2p^6,3s^2,3p^6,4s^1[/tex]
As you can see, the last level is 3 for sodium which has one electron as well as potassium whose last level is 4, therefore, they both have one valence electron.
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