Explain the following:

 does not show geometrical isomerism.

Explain the following combination of axial and equatorial bonds with cis or trans orientation for $1,2-$dimethyl cyclohexane.

$1\mathrm{e}, 2\mathrm{e}$

Explain the following combination of axial and equatorial bonds with cis or trans orientation for $1,3-$dimethyl cyclohexane

$1\mathrm{e}, 3\mathrm{e}$

Explain the following combination of axial and equatorial bonds with cis or trans orientation for $1,4-$dimethyl cyclohexane.

$1\mathrm{e}, 4\mathrm{e}$

Explain the following combination of axial and equatorial bonds with cis or trans orientation for $1,2-$dimethyl cyclohexane

$1\mathrm{e}, 2\mathrm{a}$

Explain the following combination of axial and equatorial bonds with cis or trans orientation for $1,3-$dimethyl cyclohexane

$1\mathrm{e}, 3\mathrm{a}$

Explain the following combination of axial and equatorial bonds with cis or trans orientation for $1,4-$dimethyl cyclohexane

$1\mathrm{e}, 4\mathrm{a}$

Explain the following combination of axial and equatorial bonds with cis or trans orientation for $1,3-$dimethyl cyclohexane.

$1\mathrm{a}, 3\mathrm{a}$