Answer
Please see the work below.
Work Step by Step
a) $sp - sp$ bond angle = $180^{\circ}$ Two sp hybrid orbitals are formed by the combination of one s orbital and one p orbital. In order to minimize repulsion, they orient at an angle of $180^{\circ}$.
b) $sp^{2} - sp^{2}$ bond angle = $120^{\circ}$ Three $sp^{2}$ hybrid orbitals are formed by the combination of one s orbital and two p orbitals. In order to minimize repulsion, they orient at an angle of $120^{\circ}$.
c) $sp^{3} - sp^{3}$ bond angle = $109.5^{\circ}$ Four $sp^{3}$ hybrid orbitals are formed by the combination of one s orbital and three p orbitals. In order to minimize repulsion, they orient at an angle of $109.5^{\circ}$.
