When a chemical bond is formed,there is a decrease in

Fill in the blanks:
$(i)$ In $1927$,Heitler and London proposed the ........ theory.
$(ii)$ The ${\rm{ClF}}_3$ molecule has a .... shape.
$(iii)$ The number of bonding pairs in ions with a square planar shape is .......... .
$(iv)$ The value of the dipole moment in ${\rm{HBr}}$ is .......... .

Which of the following sequences does not contain an isoelectronic species?

Which of the following does not obey the octet rule?

Match the List-$I$ with List-$II$:

List-$I$ (Classification of molecules based on octet rule)	List-$II$ (Example)
$A$. Molecules obeying octet rule	$I$. $NO, NO_2$
$B$. Molecules with incomplete octet	$II$. $BCl_3, AlCl_3$
$C$. Molecules with odd electron	$III$. $H_2SO_4, PCl_5$
$D$. Molecules with expanded octet	$IV$. $CCl_4, CO_2$

Choose the correct answer from the options given below:

In the $Al_2Cl_6$ dimer,which of the following statements is true regarding the $Al-Cl$ bonds?