The decreasing order of stability of ${\mathrm{O}}_2,{\mathrm{O}}_2^{-},{\mathrm{O}}_2^{+}$ $\mathrm{and}$ ${\mathrm{O}}_2^{2-}$is: 

1. ${\mathrm{O}}_2^{+}>{\mathrm{O}}_2>{\mathrm{O}}_2^{-}>{\mathrm{O}}_2^{2-}$

2. ${\mathrm{O}}_2^{2-}>{\mathrm{O}}_2^{-}>{\mathrm{O}}_2>{\mathrm{O}}_2^{+}$

3. ${\mathrm{O}}_2>{\mathrm{O}}_2^{+}>{\mathrm{O}}_2^{2-}>{\mathrm{O}}_2^{-}$

4. ${\mathrm{O}}_2^{-}>{\mathrm{O}}_2^{2-}>{\mathrm{O}}_2^{+}>{\mathrm{O}}_2$

Which of the following species contains an equal number of $\mathrm{\sigma }$ and $\mathrm{\pi }$ bonds?

1. ${\mathrm{HCO}}_3^{-}$

2. ${\mathrm{XeO}}_4$

3. ${\left(\mathrm{CN}\right)}_2$

4. CH₂(CN)₂

An electron-deficient compound among the following is:

Which of the following is a polar molecule?

Mark the correct order of repulsion among the following according to the VSEPR theory.

The correct order of ionic character among CaH₂, BeH₂ and BaH₂ is:

1. ${\mathrm{BeH}}_2<{\mathrm{CaH}}_2<{\mathrm{BaH}}_2$

2. ${\mathrm{CaH}}_2<{\mathrm{BeH}}_2<{\mathrm{BaH}}_2$

3. ${\mathrm{BeH}}_2<{\mathrm{BaH}}_2<{\mathrm{CaH}}_2$

4. ${\mathrm{BaH}}_2<{\mathrm{BeH}}_2<{\mathrm{CaH}}_2$

The correct shape and hybridization for XeF₄ are:

1. octahedral, sp³d²

2. trigonal bipyramidal, sp³d³

3. planar triangle, sp³d³

4. square planar, sp³d²