Question

The number and type of bonds between two carbon atoms in $Ca{C}_2$ are

• A. one sigma($\sigma$)and one pi($\pi$)bonds
• B. one sigma($\sigma$)and two pi($\pi$)bonds
• C. one sigma($\sigma$)and one and a half pi($\pi$)bonds
• D. one sigma($\sigma$)bond

Answer 1

Answer: (B)

In ${\mathrm{CaC}}_2$ we have ${\mathrm{Ca}}^{2+}$ and ${\mathrm{C}}_2^{2-}$ which are held together by ionic bonds. The structure of ${\mathrm{C}}_2^{2-}$ is $[\mathrm{C}\equiv \mathrm{C}{]}^{2-}$, thus it contains one $\sigma$ - and two $\pi$ -bonds between two carbon atoms.