You have a racemic mixture of d-2-butanol and l-2-butanol. the d isomer rotates polarized light by +13.5∘. what is the rotation of the polarization of light of your mixture? express your answer in degrees.

L- isomer is considered as the Enantiomer of d- isomer and since the d-isomer optical rotation is + 13.5° so the optical rotation of l-isomer will be the same degree but with opposite sign which equal to -13.5° 

So the degree of rotation of racemic mixture will equal 0° 

- This is because racemic mixture contains equal amount of both enantiomers