If you look at the periodic table of elements, you can see that atomic number for phosphorus is 15. It means that it has 15 electrons and 15 protons total. Now you can write configuration for P which is: 1s22s22p63s23p3. or [Ne] 3s2<span> 3p</span><span>3 </span><span>
From here, you can see that it has 5 valence electrons (s2+p3).
In the periodic table of elements the number of protons+ number of neutrons is determined as atomic mass. Atomic mass of the P is 30.
number of neutrons = atomic mass-atomic number
number of neutrons = 30-15
number of neutrons= 15 </span>
Option C coz it should be ( CNH4)2. Hope i cleared your doubt
Your answer should be C.) +2. "All the elements in Group 2 have two electrons in their valence shells, giving them an oxidation state of +2."
Credits: https://chem.libretexts.org/Core/Inorganic_Chemistry/Descriptive_Chemistry/Elements_Organized_by_Blo...
Hopefully this has helped! :)
