Define the term bond order. Give its significance.

Discuss the shapes of molecular orbitals formed by the combination of the following atomic orbitals :

 $2{\mathrm{p}}_{\mathrm{x}}+2{\mathrm{p}}_{\mathrm{x}}$

Discuss the shapes of molecular orbitals formed by the combination of the following atomic orbitals :

$2{\mathrm{p}}_{\mathrm{z}}+2{\mathrm{p}}_{\mathrm{z}}$