Question

Atomicity of white or yellow phosphorus is 4 and it forms a molecule $-P_4$. Calculate the value of the expression $\frac{x.y}{z}$, where:
$x$: Total number of vertex angles in $P_4$ molecule
$y$: Total number of lone pairs in $P_4$ molecule
$z$: Total number of $P-P$ bonds in $P_4$ molecule

Answer 1

$P_4$ molecule is tetrahedron.
Total number of vertex angleS, $x$ = 12 (each P makes 3 angles each of ${60}^o$)
Total number of lone pairs, $y$ = 4
Total number of $P-P$ bonds, $z$ = 6
so, $\frac{x.y}{z}=\frac{12\times 4}{6}=8$