To determine whether a molecule is chiral or achiral, we need to examine its symmetry and the arrangement of its substituents. Chirality refers to the property of a molecule that cannot be superimposed on its mirror image. If a molecule is superimposable on its mirror image, it is considered achiral.
In the case you mentioned, where a carbon atom is bonded to two hydrogen atoms (H) and two chlorine atoms (Cl), we can visualize the molecule as follows:
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