meso-tartaric acid is ans. optically active and achiral optically inactive and chiral optically inactive and achiral optically active and chiral

To determine the optical activity and chirality of meso-tartaric acid, we must analyze its molecular structure.

1. Understanding Chirality: A molecule is considered chiral if it has non-superimposable mirror images, which typically occurs due to the presence of chiral centers (usually carbon atoms bonded to four different substituents). If a molecule has an internal plane of symmetry, it is achiral, even if it contains chiral centers.

2. Structure of Meso-Tartaric Acid: Meso-tartaric acid contains two chiral centers but has a plane of symmetry that makes the entire molecule superimposable on its mirror image.

3. Optical Activity: Optical activity is defined as the ability of a compound to rotate the plane of polarized light. Meso-tartaric acid is optically inactive because the rotations from each chiral center cancel each other out due to its symmetry.

Based on this analysis, the correct answer is:

optically inactive and achiral.