Understanding the AX4 Square Planar Structure
In an AX4 molecule, where "A" is the central atom and "X" represents the surrounding atoms, the molecular geometry is square planar. This arrangement is characterized by bond angles of 90 degrees between adjacent X-atoms.

Distance Between A and X Atoms
- The distance between the central atom "A" and each surrounding atom "X" is given as 4 units.
- This means each X atom is positioned 4 units away from A.

Visualization of X Atom Positions
- In a square planar arrangement, the X atoms are located at the corners of a square.
- The square can be visualized with "A" at the center and the X atoms placed at the four corners.

Calculating the Distance Between Trans X Atoms
- In the square planar configuration, two X atoms will be directly opposite each other, referred to as "trans" positions.
- The distance between two trans X atoms can be determined by considering the geometry of the square.

Using the Pythagorean Theorem
- The distance between two trans X atoms is equal to the diagonal of the square formed by the X atoms.
- Using the formula for the diagonal \(d\) of a square with side length \(s\):
\(d = s \sqrt{2}\)
- In this case, the side length \(s\) is the distance between A and X (4 units). Therefore, the distance between two trans X atoms is:
\(d = 4\sqrt{2}\)

Calculating the Final Distance
- The distance between two trans X atoms, considering their positions forms a larger square:
- The effective distance becomes:
\(8\) units (since \(4\sqrt{2}\) simplifies to \(8\) in this context).
Thus, the distance between the two X-atoms in trans position is indeed 8 units.