There is free rotation about the carbons of ethane but not th of ethane. This is due to the fact that
A. the carbons in ethane are round
Balkenes do not rotate
C. the carbons in ethane are linked by double bonds
D. the carbon in ethane are smaller than those of ethane

C. the carbons in ethene are linked by double bonds

Explanation:

The reason for the lack of free rotation about the carbons of ethene is that they are linked with with double bonds.

In single bonds afforded with the ethane compound, there is free rotation.

The double bonds confer a special restriction on the rotational potential of the bonded atoms round the carbon.

- both b and d.

-since b and d are the closest coastlines then that makes it the most affected.

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i'm pretty sure its b i might be wrong though!