The number of $\sigma$ and $\pi$ bonds in $O_3$ molecule is:

Match the scientists given in List-$I$ with their discoveries given in List-$II$.

List-$I$	List-$II$
$(1)$ Kossel and Lewis	$(A)$ $VSEPR$
$(2)$ Langmuir	$(B)$ Molecular Orbital Theory
$(3)$ Sidgwick and Powell	$(C)$ Covalent Bond
$(4)$ Heitler and London	$(D)$ Octet Rule
$(5)$ $F$. Hund and Mulliken	$(E)$ Valence Bond Theory

The total number of lone pairs of electrons in $N_2O_3$ is

Back bonding in $BF_3$ does not affect

Which of the following consists of an equal number of $p\pi - p\pi$ and $p\pi - d\pi$ bonds?

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?