# In which of the following materials is hydrogen-bonding absent?

## $a .$ $\text{Hydrogen fluoride;}$ $b .$ Cl_3C-CH(OH)_2; $c .$ p-O_2NC_6H_4OH; $d .$ $\text{paradichlorobenzene.}$

In $\left(d\right)$, presumably $\text{para-dichlorobenzene}$
Hydrogen-bonding is clearly present in $H F$, $\text{chloral hydrate}$, $p - {O}_{2} N {C}_{6} {H}_{4} O H$....I think you could have specified the identity of $\left(d\right)$ better.....