The correct option is
D ![](https://s3-us-west-2.amazonaws.com/infinitestudent-images/ckeditor_assets/pictures/550243/original_007_propanedioic_acid.JPG)
In the molecule, the most acidic
H is connected directly to oxygen and not to the methylene carbon
(a) Resonance effects bond length.
(b)
cis-1-bromo-1,2-difluoroethene and
Z-1-bromo1,2-difluoroethene are geometrical isomers.
![](https://s3-us-west-2.amazonaws.com/infinitestudent-images/ckeditor_assets/pictures/550244/original_006_Geometrical_isomers.JPG)
(c)
![](https://s3-us-west-2.amazonaws.com/infinitestudent-images/ckeditor_assets/pictures/543155/original_3cn.bmp)
(d) Catechol (1,2-dihydroxybenzene) has higher boiling point than phenol due to following reasons:
i) shape
ii) molecular mass
iii) polarity - catechol is nearly twice as polar in terms of dipole moment.