Calculate the specific rotation of coniine (the toxic component of poison hemlock), if a solution containing `0.75g `in `10 mL` is placed in a `1-dm` polarimeter tube and its observed rotation at `25^(@)C(D` line) is `+1.2^(@)`.

Options

A. `+1.6^(@)`
B. `+16^(@)`
C. `+3.2^(@)`
D. `+32^(@)`

Answer

B

Explanation

Specific rotation
`= ("observed rotation"(degress))/("length"(dm)xx "concetration or density" (g//mL^(-1)))`
`[alpha]_(D)^(25^(@)) = (+1.2^(@))/((1)(0.75)/(10))=+16^(@)`
Note that the specific rotation of the enantiomer of coniine is `-16^(@)` Also note that the specific rotation is a constant and is independent of concetration and path length.