Regarding the precise measurement of specific rotation and standard stereochemical nomenclature, whi — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

There is absolutely no established predictive relationship between a molecule's structural absolute configuration (R/S or D/L) and the experimental, observed direction of its optical rotation (+ or -), making A false. A racemic mixture is a 50:50 blend where the optical rotation of one enantiomer is externally canceled by the other (B is true). D and L forms are defined relative mirror images (C is true). Rotating a Fischer projection by $90^\circ$ fundamentally swaps horizontal (wedges) and vertical (dashes) stereochemistry, artificially inverting an R center to S, or S to R (D is true).