Answer:
+15.8°
Explanation:
The formula for the observed rotation (α) of an optically active sample is
α = [α]<em>lc </em>
where
<em>l</em> = the cell path length in decimetres
<em>c</em> = the concentration in units of g/100 mL
[α] = the specific rotation in degrees
1. Convert the concentration to units of g/100 mL
2. Calculate the observed rotation