A common form of elemental phosphorus is the tetrahedral P4 molecule, where all four phosphorus atoms are

Question:

A common form of elemental phosphorus is the tetrahedral
P4 molecule, where all four phosphorus atoms are equivalent:

At room temperature phosphorus is a solid.
(a) Do you think there are any unshared pairs of electrons in the P4 molecule?
(b) How many P-P bonds are there in the molecule?
(c) Can you draw a Lewis structure for a linear P4 molecule that satisfies the octet rule?
(d) Using formal charges, what can you say about the stability of the linear molecule versus that of the tetrahedral molecule?