Chapter 6, Problem 66AP

Calcium carbide $\left({\text{CaC}}_{\text{2}}\right)$ is an intermediate in the manufacturing of acetylene $\left({\text{C}}_{\text{2}}{\text{H}}_{\text{2}}\right)$ . It is the calcium salt of the carbide (also called acetylide) ion $\left({\text{C}}_2^{2-}\right)$ . What is the electron configuration of this molecular ion? What is its bond order?