Water $(H_2O)$ is a liquid while hydrogen sulphide $(H_2S)$ is a gas because

Hydrogen bonding is formed in compounds containing hydrogen and

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 points of $HF, HCl, HBr$ and $HI$ are $293 \ K, 189 \ K, 200 \ K$ and $238 \ K$ respectively.
$(a)$ Which type of intermolecular forces are present in the molecules $HF, HCl, HBr$ and $HI$?
$(b)$ Looking at the trend of boiling points of $HCl, HBr$ and $HI$,explain out of dipole-dipole interaction and London interaction,which one is predominant here.
$(c)$ Why is the boiling point of hydrogen fluoride highest while that of hydrogen chloride lowest?

Correct decreasing order of boiling point of given compounds:
$I. \ HCl$
$II. \ H_2O$
$III. \ HF$
$IV. \ NH_3$

Among $H_2O$,$H_2S$,$H_2Se$ and $H_2Te$,the one with the highest boiling point is

Why does $NH_{3}$ form hydrogen bond but $PH_{3}$ does not?