A solution of an unknown compound has a concentration of 5.0 g/ml and an observed rotation of -25° in a 3.0 dm polarimeter tube. Determine its specific rotation.

7.000 g/mL of a substance has an observed rotation of +120.0°. In a polarimeter tube that is 10.00 cm long, calculate its specific rotation.

A solution of a chiral molecule gives a rotation about 179.9º. Propose a way to tell if the rotation is +180º or −180º.

A solution was prepared by dissolving 1.8 g of (−)-glyceraldehyde in 9.00 mL of water. The solution was placed in a 100-mm cell and the rotation was then measured at 25℃ using the sodium D line. If the rotation observed was −1.74º, calculate the specific rotation of (−)-glyceraldehyde.