existance

[Bethel Tesfamicael]

can a pi bond exist without a sigma bond and can a sigma bond exist without a pi bond?

[Elisabeth Atwater 2D]

Sigma bonds can exist without pi bonds (that's when you have single bonds) but pi bonds need sigma bonds to exist. Pi bonds are in double and triple bonds, which each have a sigma bond, so you can't have a pi bond with no sigma bond.

[Brandon Li]

Think of it this way:

In the case of a triple bond, the bond order will always be

1: Sigma bond
2: Pi Bond
3: Pi bond