What is the bond order of the carbon – carbon bond in the acetylene molecule?

What is the bond order of the carbon- carbon bond in the acetylene molecule? _________ (enter a number)
Which species has the shortest carbon-carbon bond, C2H2, C2H5Cl, or C2H4?
ethylene
chloroethane
acetylene
Which species has the weakest carbon – carbon bond, C2H2, C2H5Cl , or C2H4?
ethylene
chloroethane
acetylene