Answers:
Hydrogen bond is formed when positive end of one molecule attracted negative end of other molecule. The concept is similar to magnetic attraction where opposite poles attract each other.
Step-by-step explanation:
While understanding hydrogen bond, two terms are important, one is electronegativity (tendency of atoms to attract electrons towards itself) and other is dipole (separation of positive and negative charge in a molecule). Hydrogen bond is always formed between hydrogen atom and other atoms having electronegativity different than hydrogen.
Differ from Ionic and Covalent Bonds:
Hydrogen bond is weaker than ionic and covalent bond. Ionic and covalent bonds are intramolecular (within the molecule) whereas hydrogen bond is intermolecular (between molecules).
Example:
Formation of hydrogen bonding in water.