If $1$ gram of each of the following gases are taken at $\mathrm{STP}$, which of the gases will occupy (a) greatest volume and (b) smallest volume?

$\mathrm{CO}, {\mathrm{H}}_2\mathrm{O}, {\mathrm{CH}}_4, \mathrm{NO}$

Use the information and data given below to answer the questions (a) to (c):

• Stronger intermolecular forces result in higher boiling point.

• Strength of London forces increases with the number of electrons in the molecule.

• Boiling point of $\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}$ and $\mathrm{HI}$ are $293 \mathrm{K}, 189 \mathrm{K}, 206 \mathrm{K}$ and $238 \mathrm{K}$ respectively.

(a) Which type of intermolecular forces are present in the molecules $\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}$ and $\mathrm{HI}$?
 

Use the information and data given below to answer the questions (a) to (c):

• Stronger intermolecular forces result in higher boiling point.

• Strength of London forces increases with the number of electrons in the molecule.

• Boiling point of $\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}$ and $\mathrm{HI}$ are $293 \mathrm{K}, 189 \mathrm{K}, 206 \mathrm{K}$ and $238 \mathrm{K}$ respectively.

(b) Looking at the trend of boiling points of $\mathrm{HCl}, \mathrm{HBr}$ and $\mathrm{HI}$, explain out of dipole-dipole interaction and London interaction, which one is predominant here.
 

Use the information and data given below to answer the question.

• Stronger intermolecular forces result in higher boiling point.

• Strength of London forces increases with the number of electrons in the molecule.

• Boiling point of $\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}$ and $\mathrm{HI}$ are $293 \mathrm{K}, 189 \mathrm{K}, 206 \mathrm{K}$ and $238 \mathrm{K}$ respectively.

Why is boiling point of hydrogen fluoride highest while that of hydrogen chloride lowest?