Identify a molecule with an incomplete octet from the following.

Statement $(A)$ $CO_2$ has no dipole moment,whereas $SO_2$ and $H_2O$ have dipole moment.
Statement $(B)$ $SnCl_2$ is ionic,whereas $SnCl_4$ is covalent.
Which of the following is correct?

Which of the following orders is not correct?

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

Which one of the following is not correct for the reaction given below:
$NH_3 + BF_3 \to NH_3.BF_3$

Arrange the bonds in order of increasing ionic character in the molecules: $LiF$,$K_2O$,$N_2$,$SO_2$,and $ClF_3$.