Which of the following pairs of ions are isoelectronic and isostructural?

1. ${\mathrm{CO}}_3^{2-},$ ${\mathrm{SO}}_3^{2-}$

2. ${\mathrm{ClO}}_3^{-},$ ${\mathrm{CO}}_3^{2-}$

3. ${\mathrm{SO}}_3^{2-},$ ${\mathrm{NO}}_3^{-}$

4. ${\mathrm{ClO}}_3^{-},$ ${\mathrm{SO}}_3^{2-}$

Choose the compound which has a maximum bond angle at nitrogen among the following:
1. ${\mathrm{NO}}_2$
2. ${{\mathrm{NO}}_2}^{-}$
3. ${{\mathrm{NO}}_2}^{+}$
4. ${{\mathrm{NO}}_3}^{-}$

The correct order of bond order in the following species is:

A molecule among the following that has the maximum dipole moment is:

Which one of the following species has a plane triangular shape?

An electron-deficient compound among the following is:

Which of the following is a polar molecule?

A paramagnetic molecule among the following is: