Which of the following are isostructural pairs ?
$\mathrm{SO}_4^{2-}$ and $\mathrm{CrO}_4^{2-}$
$\mathrm{SiCl}_4$ and $\mathrm{TiCl}_4$
$\mathrm{NH}_3$ and $\mathrm{NO}_3^{-}$
$\mathrm{BCl}_3$ and $\mathrm{BrCl}_3$

Among the following, the number of halide(s) which is/are inert to hydrolysis is _______.

According to molecular theory, the species among the following that does not exist is:

According to MO theory, number of species/ions from the following having identical bond order is _____:$\mathrm{CN}^{-}, \mathrm{NO}^{+}, \mathrm{O}_2, \mathrm{O}_2^{+}, \mathrm{O}_2^{2+}$

Amongst the following the number of oxide(s) which are paramagnetic in nature is $\mathrm{Na}_2 \mathrm{O}, \mathrm{KO}_2, \mathrm{NO}_2, \mathrm{~N}_2 \mathrm{O}, \mathrm{ClO}_2, \mathrm{NO}, \mathrm{SO}_2, \mathrm{Cl}_2 \mathrm{O}$

Consider the following sulphure based oxoacids. $$
\mathrm{H}_2 \mathrm{SO}_3, \mathrm{H}_2 \mathrm{SO}_4, \mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_8 \text { and } \mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_7 \text {. } $$
...

The sum of number of lone pairs of electrons present on the central atoms of $\mathrm{XeO}_3, \mathrm{XeOF}_4$ and $\mathrm{XeF}_6$ is

The number of interhalogens from the following having square pyramidal structure is : $$ \mathrm{ClF}_3, \mathrm{IF}_7, \mathrm{BrF}_5, \mathrm{BrF}_3, \mathrm{I}_2 \mathrm{Cl}_6, \mathrm{IF}_5, \mathrm{ClF}, \mathrm{ClF}_5 $$

The number of paramagnetic species among the following is $\_\_\_\_$ . $\mathrm{B}_2, \mathrm{Li}_2, \mathrm{C}_2, \mathrm{C}_2^{-}, \mathrm{O}_2^{2-}, \mathrm{O}_2^{+} ;$and $\mathrm{He}_2^{+}$

Consider, $\mathrm{PF}_5, \mathrm{BrF}_5, \mathrm{PCl}_3, \mathrm{SF}_6,\left[\mathrm{ICl}_4\right]^{-}, \mathrm{ClF}_3$ and $\mathrm{IF}_5$. Amongst the above molecule(s)/ion(s), the number of molecule(s)/ion(s) having $\mathrm{sp}^3 \mathrm{~d}^2$ hybridisation is $\_\_\_\_$ .