Presence of lone pairs distorts the geometry of a molecule. Explain with example.

What is the effect of the following ionisation process on the bond order in ${\mathrm{C}}_2$?

${\mathrm{C}}_2\stackrel{ }{\to }{{\mathrm{C}}_2}^{+}+{\mathrm{e}}^{-}$

What is the effect of the following ionisation process on the bond order in ${\mathrm{O}}_2$?  

${\mathrm{O}}_2\stackrel{ }{\to }{{\mathrm{O}}_2}^{+}+{\mathrm{e}}^{-}$

Arrange the following according to bond length giving reasons.

$\mathrm{HF}, \mathrm{HCl}, \mathrm{HBr}$and $\mathrm{H}-\mathrm{I}$.

Arrange the following according to bond length giving reasons.

$\mathrm{C}-\mathrm{C}, \mathrm{C}=\mathrm{C}$and $\mathrm{C}\equiv \mathrm{C}$.

Arrange the following according to bond length giving reasons.

$\mathrm{C}-\mathrm{H}$ bond length in ${\mathrm{CH}}_4, {\mathrm{C}}_2{\mathrm{H}}_4$and ${\mathrm{C}}_2{\mathrm{H}}_2$.