The hydrogen atoms of a water molecule are bonded to the oxygen atom by bonds, whereas neighboring water molecules are held together by bonds. 79)
a. polar covalent; ionic
b. hydrogen; polar covalent
c. ionic; covalent
d. polar covalent; hydrogen

Option d, Polar covalent, hydrogen bond

Explanation:

Chemical formula of water is . In water molecules, two hydrogen atoms are bonded to oxygen atom by two covalent bonds. Covalent bond is formed by sharing of electrons. As oxygen atom is more electronegative than hydrogen, therefore, shared electrons are attracted towards oxygen atoms. Because of this covalent bonds between hydrogen and oxygen are polar in nature.

Hydrogen bond is present between the hydrogen atom bonded to electronegative atoms, O, F, N and the electrogetive atom of another molecule. As in water molecules hydrogen is bonded to 'O' atoms, therefore hydrogen bonds exist between two water molecules. Because of presence of hydrogen bond, boiling point of water is very high.