Test: Hydrogen Bonding (May 28) - JEE MCQ

All these are soluble in water due to intermolecular H-bonding.

(a) Intermolecular H-bonding, boiling point increases with molecular weight for compounds within the same family.
(b) H-bonding is absent is CH₃CH₂CH₃.
(c) Methanol is the larger molecule but H₂O has more H-bonding because of two O—H bonds.
Thus, boiling point of H₂O(ll) > CH₃OH(l).
(d) Molecular weight of butanol is much higher and overcomes attractive forces of butanol.

O — H group is attached to (ene) is m ost a cidic and thus, has maximum intermolecular H-bonding.

CH₃CH₂OH is in liquid state due to association as a result of intermolecular H-bonding.

One water molecule is directly attached to four water molecules. Thus, coordination number of water is 4.

I. Intermolecular H-bonding makes boiling point higher than that of I. Thus, I is more volatile 

II. Ortho nitrophenol is more volatile than para nitrophenol because O-Nitrophenol has intramolecular hydrogen bonding whereas para nitrophenol has inter molecular H bonding and so boils relatively at higher temperature
(c) BP of H₂O > > H₂S
(d) BP of CH₃CH₂OH (due to H-bonding) > > CH₃— O — CH₃ 

(a) When liquid water changes to ice, there is an air gap inside the cage formed due to intermolecular H-bonding. Thus, volume of ice > volume of water.

Hence, density (ice) < density (water).
Thus, ice floats on water - hydrogen bonding plays its role.
(b) In gaseous phase, basicity of 1° < 2° < 3° amines due to increase of electron density at N-atom

But in aqueous (H₂O) solvent, RNH₂ is stabilised by solvation. Thus 1° amine is more

basic than 3° amine (3° < 1° < 2°) amines.
(c) l₊ (positive inductive effect) explains this

Dimer due to intermolecular H- bonding.

I. CCI₃CH (OH)₂ with two — OH groups on same carbon atom is stable due to intramolecular H-bonding.

n-butane lacks H-bonding. Hence, its boiling point is least. 

due to difference in polar H⁺ for H-bonding.
Boiling point of CH₃CH₂CH₂CH₂OH > H₂O due to much larger size of alcohol.