State whether the following statements are true or false.
a. `D` and `L` stereoisomers are enantiomers.
b. `D` enantiomer rotates the plane-polarised light to the right and `L` enantiomer to the left.
c. Conversion of an erythro to a threo stereoisomer always occur by inversion at one chiral `C`.
d. A racemate can be distinguished from a meso or a chiral compound by an attempted resolution.
e. Racemisation of an enantiomer can only occure by breaking of at least one bond to the chiral centre.
f. A reaction catalysed by an enzyme always gives an `O.A` product.
g. When an achiral molecule reacts to give achiral molecule, the product is always racemic
h. In chemical reactions, the change from an `S` reactant to an `R` product always signals an inversion of configuraion.
i. An optically inactive substance must be achiral.
j. An achiral compound can have chiral centres.
K. A compound with `S` configuration is the `(-)` enantiomer.