Question

given this table of electronegativities:

atom	electronegativity
c	2.6
n	3.0
o	3.4
f	4.0
s	2.6
br	3.0
cl	3.2
p	2.2
i	2.7

list the following molecules in order of increasing dipole moment: hf, ni₃, co, co₂

Explanation:

Step1: Recall dipole - moment concept

Dipole moment is related to electronegativity difference and molecular geometry. Non - polar molecules have zero dipole moment.

Step2: Analyze $CO_2$

$CO_2$ is a linear molecule with a symmetrical structure. The electronegativity difference between C and O is $3.4 - 2.6=0.8$, but due to its linear geometry ($O = C = O$), the bond dipoles cancel out, so $\mu_{CO_2}=0$.

Step3: Analyze $CO$

For $CO$, the electronegativity difference between C and O is $3.4 - 2.6 = 0.8$. It is a polar molecule with a non - zero dipole moment.

Step4: Analyze $NI_3$

In $NI_3$, the electronegativity difference between N and I is $3.0 - 2.7=0.3$. The molecule has a trigonal pyramidal geometry, so it has a non - zero dipole moment.

Step5: Analyze $HF$

In $HF$, the electronegativity difference between H and F is $4.0 - 2.2 = 1.8$. It is a highly polar molecule with a large dipole moment.

Step6: Compare dipole moments

Based on the above analysis, the order of increasing dipole moment is $CO_2

Answer:

$CO_2