Question

Atomicity to white or yellow phosphorus is 4 and it is represented as ${ P }_{ 4 }$ molecule. Calculate the value of the expression $\dfrac { x.y }{ z }$ regarding this molecule.
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

Hint: In this question, it is necessary that you first draw the structure of a ${ P }_{ 4 }$ molecule. Then try to find the value of each quantity given in the question and finally apply those in the formula given. You will easily get the answer to your question.

Complete step by step answer:

First, we should look at the structure of a phosphorus molecule.

Atomicity of white or yellow phosphorus is 4 and it is represented as ${ P }_{ 4 }$ molecule.
Where x: Total number of vertex angles in ${ P }_{ 4 }$ molecule = number of P atoms $\times$ number of vertex angles per P atom = 4 $\times$ 3 = 12
y: Total number of lone pairs in ${ P }_{ 4 }$ molecule = number of P atoms $\times$ number of lone pairs per P atom = 4 $\times$ 1 = 4
z: Total number of P-P bonds in ${ P }_{ 4 }$ molecule = 6

Now put the value in the given expression = $\dfrac { x.y }{ z }$
This will be equal to $\dfrac { 12\times 4 }{ 6 }$ = 8

Therefore, we can say that the value of the expression $\dfrac { x.y }{ z }$ regarding this molecule is 8.

Note: You should also know that White phosphorus is a translucent waxy solid that quickly becomes yellow when exposed to light. For this reason, it is also called yellow phosphorus. It glows greenish in the dark (when exposed to oxygen) and is highly flammable and pyrophoric (self-igniting) upon contact with air.