Complex sentence: Tartaric acid contains two asymmetric centers, but two of the configurations are equivalent and together are called meso compounds meso -, this configuration is not optically active, while the remaining two configurations are d-and l-mirror images.
Split into simpler sentences: Tartaric acid contains two asymmetric centers, but two of the configurations are equivalent and together are called meso compounds. This configuration is not optically active, while the remaining two configurations are d-and l-mirror images.