In order to find out the number of electrons present in s orbital of Phosphorous we have to write the electronic configuration of phosphorous.
As the Atomic number of Phosphorous is 15 so it will have 15 electrons in neutral state. So,
P = 15 = 1s², 2s², 2p⁶, 3s², 3p³
Now analyzing electronic configuration, we found that it contains 3 s orbitals, i.e. 1s, 2s and 3s, and each s orbital is completely filled with two electrons each.
Result:
Therefore, a total of six electrons are present in all s orbitals of neutral Phosphorous Atom.