Question

The correct sequence of polarity of the following molecule
a) Benzene
b) Inorganic Benene
c) $PC{l}_3{F}_2$
d) $PC{l}_2{F}_3$
(Where, $P=$ polar, $NP=$ non-polar)

• A. $1P,2NP,3NP,4P$
• B. $1NP,2NP,3NP,4P$
• C. $1NP,2P,3NP,4P$
• D. $1NP,2P,3P,4NP$

Answer 1

Answer: (B)

$1NP,2NP,3NP,4P$

Option $B$ is correct

a) Benzene: Benzene is a non-polar because it is a hydrocarbon that contain only $C-C$ and $C-H$ bonds and hydrocarbons are non-polar.

b) Inorganic Benzene: Inorganic Benzene also called as Borazole with the chemical formula $B_3{N}_3{H}_6$ which is a colourless liquid, the electron arrangement of these cyclic compound is such that there are alternate $B=N$ bond like $C=C$ in the benzene with a $H$ attached to every $N$ and $B$. Thus Borazole is completely a non-polar compound.

$PC{l}_3{F}_2$ and $P{F}_3{Cl}_2$: In case of $PC{l}_3{F}_2$, the molecule is non-polar, even though the fluorine atoms are slightly more electro-negative than the chlorine. This could be explain in a couple ways. The more intuitive approach is to consider how the presence of two fluorine atoms would create symmetry. The less intuitive, but more accurate, process would be to realize that the structure of the molecule is divided in to two non-polar structure(trigonal planer and linear). With other molecules, like $P{F}_3{Cl}_2$ it's not possible to divide it in to non-polar shapes. The repulsion between the fluorine atom is greater than that between the chlorine. Thus $P{F}_3{Cl}_2$ is polar.