Which has highest boiling point?

H20, H2S, H2Se, H2Te
i know its H20, but why? is it because its dipole dipole? does it have to do with electronegative, or polarity?

It has to do with hydrogen bonding and polarity of the molecule as well as with the molar mass. Increasing molar mass generally means higher boiling points. So in this case, decreasing the molar mass would mean lower boiling points. But H2O is way out of line since H2S is a gas H2O should be a gas even at lower temperatures BUT it isn't. It's good to remember that

a)in the same column (as these compounds are), the size makes the larger difference (here it is the size and the molar mass).
b) in the same row, its the electronegativity.

Why do oxygenated fuels contain less energy than hydrocarbons?

To determine the boiling point of a compound, we need to consider several factors, including molecular size, intermolecular forces, and polarity.

In the case of the given compounds (H2O, H2S, H2Se, and H2Te), the boiling point follows the trend H2Te < H2Se < H2S < H2O. The reason for this trend lies in the intermolecular forces present.

H2O, or water, has the highest boiling point among the given compounds. Water molecules exhibit hydrogen bonding, which is a type of intermolecular force that occurs when a hydrogen atom is bonded to a highly electronegative atom (oxygen in this case). This creates a significant dipole-dipole attraction between water molecules. Hydrogen bonding is a stronger intermolecular force compared to the other compounds' intermolecular forces.

On the other hand, the other compounds (H2S, H2Se, and H2Te) lack significant hydrogen bonding. They exhibit weaker dipole-dipole forces known as van der Waals forces or London dispersion forces. Van der Waals forces result from temporary dipoles that occur due to the unequal distribution of electrons at any given point in time.

Since water has stronger intermolecular forces (hydrogen bonding) compared to the other compounds, it requires more energy to overcome these attractive forces, leading to a higher boiling point. This is why H2O has the highest boiling point among the given compounds.

In summary, the presence of stronger intermolecular forces, such as hydrogen bonding, increases the boiling point of a compound.