Test: Hydrogen Bonding - JEE MCQ

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

Due to intermolecular H-bonding at two terminals boiling point of glycol is maximum.

(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.

H-bonding is between polar and electronegative 0, N and F C-atom or H attached to C is not polar. Thus, (a), (c), (d) are incorrect.

1. Enoiic H, acidic and polar takes part in H-bonding.
2. 3° alcohol least acidic maximum basic.
3. Carbonyl oxygen is not involved.
4. Acidic and polar H, takes part in H-bonding.

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

F, O and N are electronegative elements. Thus, HF molecules are associated by intermolecules H-bonding giving it a liquid state and thus highest boiling point out of HF, HCl.HBr and HI.
Similarly, H₂O has highest boiling point, and NH₃ has highest boiling point.

A hydrogen bond is a weak type of force that forms a special type of dipole-dipole attraction which occurs when a hydrogen atom bonded to a strongly electronegative atom exists in the vicinity of another electronegative atom with a lone pair of electrons.
F is the most electronegative atom. Hence hydrogen bond is shortest in F - H ........F.

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.

HCI: EN of Cl is smaller, hence less polar than HF.
CH₄ :non-polar
CH₃COO^- : H attached to C-atom is non-polar hence
HCI, CH_4, CH₃COO^- — lack H-bonding.

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.

(a) intramolecular 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.