Question

1. Sketch an interaction of two sp3 atomic orbitals to form a bonding sigma molecular orbital.

2. Sketch an interaction of two p atomic orbitals to form an anti-bonding pi molecular orbital

Answer 1

1) sp3 atomic orbitals have the shape of an unbalanced p orbital, so a bonding sigma molecular orbital would look like
2) Two p orbitals overlap sideways either constructively or destructively, depending on how the p orbitals are oriented relative to their amplitudes. Each p orbital will look like this by itself:
If two p orbitals overlap constructively (+ to + and - to -), they form a bonding pi bond. Vice-versa, if they overlap destructively (+ to -, and - to +), they form an antibonding pi bond.

Here is what the bonding pi MO looks like:
And here's an anti-bonding pi MO::