AP BIOLOGY

Detailed explanation-1: -Strong linkages-called covalent bonds-hold together the hydrogen (white) and oxygen (red) atoms of individual H2O molecules. Covalent bonds occur when two atoms-in this case oxygen and hydrogen-share electrons with each other.

Detailed explanation-2: -A: The oxygen atom shares one pair of valence electrons with each hydrogen atom. Each pair of shared electrons represents one covalent bond, so two covalent bonds hold the water molecule together.

Detailed explanation-3: -Single covalent bond is the bond which is formed by sharing of one electron pair between two atoms in which each atom contributes one electron. It is represented by putting short line between two atoms. For example, consider the formation of molecule. Hydrogen atom has one electron in its valence shell.

Detailed explanation-4: -Oxygen molecule has two oxygen atoms. Each O atom shares 2 electrons to form two covalent bonds out of which one is sigma bond and other is pi bond. Sigma bond is formed by axial overlap 2p atomic orbitals of oxygen and pi bond is formed of lateral overlap of 2p atomic orbitals of oxygen.