Which of the following is a Lewis acid?

The formal charges of $N_{(1)}$,$N_{(2)}$ and $O$ atoms in the structure shown below are respectively:
$:N_{(1)}=N_{(2)}=\ddot{O}:$

Sodium bicarbonate $(NaHCO_3)$ has:

Which of the following statement$(s)$ is/are correct? [$T$ for True and $F$ for False$]$
$(a)$ Hybrid orbitals form stronger bonds than pure atomic orbitals.
$(b)$ Canonical structures have a difference in the arrangement of atoms $w.r.t.$ each other.
$(c)$ Any symmetrical molecule always contains the same bond angle.
$(d)$ $VSEPR$ theory can explain the square planar geometry of $XeF_4$.

In which of the following,the formal charge is $NOT$ on the central atom in the most stable canonical form?

Which of the following species among $BF_3, SnCl_2, SnCl_4$ act as Lewis acids?