Achiral stereoisomer(s) is(are) possible for 
Step 1: Understanding achirality.
Achirality refers to the lack of chirality or handedness in a molecule. A molecule is achiral if it has a plane of symmetry or an inversion center.
Step 2: Analyzing the options.
- Option (D) \( \text{HOCO}_2\text{H} \) (formic acid) is achiral because it has a plane of symmetry.
- Other options involve molecules that are potentially chiral.
Step 3: Conclusion.
The achiral stereoisomer is (D).

Consider the following molecule (X).
The Structure X is? 
How many different stereoisomers are possible for the given molecule? 
One mole of a monoatomic ideal gas starting from state A, goes through B and C to state D, as shown in the figure. Total change in entropy (in J K\(^{-1}\)) during this process is ............... 
The number of chiral carbon centers in the following molecule is ............... 
A tube fitted with a semipermeable membrane is dipped into 0.001 M NaCl solution at 300 K as shown in the figure. Assume density of the solvent and solution are the same. At equilibrium, the height of the liquid column \( h \) (in cm) is ......... 
An electron at rest is accelerated through 10 kV potential. The de Broglie wavelength (in A) of the electron is .............