The question is incomplete, the complete question is:
If a 6.00 g sample of an optically pure compound was dissolved in 40.0 mL of
and the observed rotation was +3.30°, measured in a 10.0 cm (1.00 dm) polarimeter tube, how would one determine the specific rotation of the pure compound?
<u>Answer: </u>The specific rotation of the pure compound is 
<u>Explanation:</u>
To calculate the specific rotation of a pure compound, we use the equation:
![[\alpha]=\frac{\alpha_{\text{observed}}}{C\times l\text{( in dm)}}](https://tex.z-dn.net/?f=%5B%5Calpha%5D%3D%5Cfrac%7B%5Calpha_%7B%5Ctext%7Bobserved%7D%7D%7D%7BC%5Ctimes%20l%5Ctext%7B%28%20in%20dm%29%7D%7D)
where,
= specific rotation of a pure compound
= observed rotation of the compound = [ex]+3.30^o[/tex]
C = concentration in g/mL = 6.00 g/40 mL = 0.15 g/mL
l = path length = 1.00 dm
Putting values in above equation, we get:
![[\alpha]=\frac{+3.30^o}{0.15\times 1.0}](https://tex.z-dn.net/?f=%5B%5Calpha%5D%3D%5Cfrac%7B%2B3.30%5Eo%7D%7B0.15%5Ctimes%201.0%7D)
![[\alpha]=+22^o](https://tex.z-dn.net/?f=%5B%5Calpha%5D%3D%2B22%5Eo)
Hence, the specific rotation of the pure compound is 