[JNW2]

1. Why do ketone and aldehyde (carbonyl) have greater boiling point than the others (ether,alkyne)?

Because of dipole moment ? Is C double bond O greater dipole moment than normal single bond?


2. Why does amide have greater B.P.  than carboxylic acid?

Because of dipole moment  (difference EN between O and N) or the number of / strength in H bond ?


3. Why does ketone have little more B.P. than aldehyde?
 Dipole moment again?

[AWK]

Think also about hydrogen bonds when possible.

[Enthalpy]

1. Angles also influence the dipole moment, especially if two bonds are polarized.
3. The groups attached to the carbonyl can ease the polarisation.

[JNW2]

In Q2,Q3
Is resonance related to boiling point ?

[Enthalpy]

You can understand polarisation as a resonance if you wish. It's even a common explanation. But keep in mind that the electrons are static in a so-called resonance.

Oxygen attracts electrons not only from the carbonyl carbon, but also a bit from the next atoms. If more atoms bind to the carbonyl (ketone versus aldehyde), the polarisation is easier and stronger. As well, the electron displacement operates over a bigger distance, which also contributes to a bigger dipole moment.

[JNW2]

You can understand polarisation as a resonance if you wish. It's even a common explanation. But keep in mind that the electrons are static in a so-called resonance.

Oxygen attracts electrons not only from the carbonyl carbon, but also a bit from the next atoms. If more atoms bind to the carbonyl (ketone versus aldehyde), the polarisation is easier and stronger. As well, the electron displacement operates over a bigger distance, which also contributes to a bigger dipole moment.

Is that about "symmetry "? (Like the addition surface area for van der waals force?)
Because the non polar of aldehyde grow one direction, but ketone
there are two directions ?

[Enthalpy]

Because in a ketone, oxygen has more nearby atoms to suck electrons from.