Identify which molecule in each of the following pairs has stronger $H$-bonding:
$(i)$ $H_2O$ and $H_2S$
$(ii)$ $NH_3$ and $PH_3$
$(iii)$ $HF$ and $HCl$

(A) $(i)$ $H_2O$ has stronger $H$-bonding than $H_2S$ because oxygen is more electronegative than sulfur.
$(ii)$ $NH_3$ has stronger $H$-bonding than $PH_3$ because nitrogen is more electronegative than phosphorus.
$(iii)$ $HF$ has stronger $H$-bonding than $HCl$ because fluorine is more electronegative than chlorine.
In all cases,the strength of $H$-bonding depends on the electronegativity of the atom bonded to the hydrogen atom.