Increasing order of boiling point of the given compounds are :
CH3CH2CH2CH3 , H6C2-O-C2H5 , CH3CH2CH2CHO , CH2CH2CH2OH.
Hope this will help you !!!

Boiling point is a measure of the intermolecular forces between molecules. The stronger the intermolecular forces, the higher the boiling point. In general, intermolecular forces can be categorized into three types:

1. London Dispersion Forces (LDF): These are the weakest intermolecular forces and exist in all molecules. LDFs are caused by temporary fluctuations in electron distribution, resulting in temporary dipoles. The strength of LDFs increases with the size and shape of the molecule.

2. Dipole-Dipole Interactions: These forces exist in polar molecules where the positive end of one molecule attracts the negative end of another molecule. The strength of dipole-dipole interactions depends on the magnitude of the dipole moment.

3. Hydrogen Bonding: Hydrogen bonding is a special type of dipole-dipole interaction that occurs when a hydrogen atom is bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine). Hydrogen bonding is stronger than regular dipole-dipole interactions.

Now, let's analyze the given compounds and determine their boiling points based on the intermolecular forces present.

1. CH3CH2CH2CHO (Propionaldehyde):
- This compound contains a polar carbonyl group (C=O) and a non-polar alkyl chain.
- The polar carbonyl group can participate in dipole-dipole interactions with other molecules.
- The alkyl chain can only contribute to London Dispersion Forces (LDFs).
- The boiling point of propionaldehyde is higher than non-polar compounds but lower than compounds with hydrogen bonding or additional polar groups.

2. CH3CH2CH2CH2OH (Butanol):
- This compound contains a polar hydroxyl group (OH) and a non-polar alkyl chain.
- The polar hydroxyl group can participate in both dipole-dipole interactions and hydrogen bonding.
- The alkyl chain can contribute to London Dispersion Forces (LDFs).
- The boiling point of butanol is higher than propionaldehyde due to the presence of hydrogen bonding.

3. CH3CH2CH2CH3 (Butane):
- This compound contains only non-polar alkyl chains.
- The only intermolecular forces present are London Dispersion Forces (LDFs).
- The boiling point of butane is lower than both propionaldehyde and butanol due to the absence of polar groups or hydrogen bonding.

4. H6C2-O-C2H5 (Diethyl ether):
- This compound contains a polar oxygen atom and two non-polar ethyl groups.
- The polar oxygen atom can participate in dipole-dipole interactions.
- The ethyl groups can contribute to London Dispersion Forces (LDFs).
- The boiling point of diethyl ether is higher than butane but lower than both propionaldehyde and butanol due to the absence of hydrogen bonding.

Therefore, the increasing order of boiling points for the given compounds is as follows:
Butane < ch3ch2ch2cho="" />< h6c2-o-c2h5="" />< ch3ch2ch2ch2oh="" />