The specific rotation of a pure substance is 1.68°. what is the specific rotation of a mixture containing 75% of this isomer and 25% of the isomer?
a) +1.68°
b) 0°
c) +1.26°
d) +0.84°
e) +.042°

Specific rotation of mixture = D. 0.84 °

Explanation:

Enantiomeric excess = % of one enantiomer - % of the other enantiomer = 75-25 % = 50 %

Also,

Enantiomeric excess =

Optical rotation of pure enantiomer = 1.68  °

Applying the values as:-

Specific rotation of mixture = 0.84 °

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e