What type of bonds exist between the two carbon atoms in calcium carbide?

The electronic configuration of three elements $A$,$B$,and $C$ are given below. The bond between $B$ and $C$ will be:
$A: 1s^2, 2s^2, 2p^6$
$B: 1s^2, 2s^2, 2p^6, 3s^2, 3p^3$
$C: 1s^2, 2s^2, 2p^6, 3s^2, 3p^5$

Which one of the following has the longest covalent bond distance?

$BCl_3$ does not exist as a dimer,whereas $BH_3$ exists as a dimer $(B_2H_6)$ because ....

Which of the following is the strongest bond?

Explain the polar covalent bond with the help of a suitable example.