Ionic and covalent bonds are present in

The structure of $B_3N_3H_6$ (borazine) is as follows. How many derivative structures of $B_3N_3H_4X_2$ can be derived from the basic structure by the replacement of two hydrogen atoms?

Which one of the following is a Lewis acid?

Which bond is shorter: $C=O$ or $N=O$? Why?

The incomplete Lewis representation of $CO_3^{2-}$ is given below. The formal charges on atoms marked as $a$,$b$,and $c$,respectively,are

Which of the following is the correct increasing order of $O-O$ bond length in $O_2$,$O_3$,and $H_2O_2$?