The number and type of bonds in $C_2^{2-}$ ion in $CaC_2$ are

Which of the following statements is correct for a covalent bond?

When two atoms with electrons having the same spin approach each other for bonding,which of the following will occur?

Briefly describe the valence bond theory of covalent bond formation by taking an example of hydrogen.

The bond dissociation energy of $B-F$ in $BF_3$ is $646 \ kJ \ mol^{-1}$ whereas that of $C-F$ in $CF_4$ is $515 \ kJ \ mol^{-1}.$ The correct reason for higher $B-F$ bond dissociation energy as compared to that of $C-F$ is

Indicate the nature of bonding in diamond.