Answer:
Hydrogen bond is a force of attraction between the hydrogen atom of one molecule and the oxygen of other molecule in case of water.
Water properties like boiling point and density are much bigger than molecules containing hydrogen with similar molecular weight. Water is liquid at 1 atmosphere and 4 to 100 °C due to the hydrogen bonds.
Those hydrogen bonds confere polarity to water, and so, it is an important solvent for other polar products. We say water is the universal solvent.
Hydrogen bond is important in the formation of proteins and their functions, and so is much important for life.
