Which of the following species contain a C4 axis and a σh plane? Choose all that apply.

[ICl4]-
SiCl4
XeF4
GeH4
[PO4]3

GeH4

To determine which of the given species contain a C4 axis and a σh plane, we need to understand the symmetry elements of each species.

A C4 axis refers to a rotation axis of a molecule that leads to the molecule being indistinguishable after rotating it by 360 degrees divided by four (90 degrees).

A σh plane refers to a horizontal mirror plane, meaning that if a molecule is reflected across this plane, it remains unchanged.

Let's examine each species one by one:

[ICl4]-:
To determine the symmetry elements, we need to consider the central atom, which is iodine (I) in this case. Iodine (I) belongs to the C4v point group, which contains a C4 axis but does not contain a σh plane. Therefore, [ICl4]- does not contain a C4 axis and a σh plane.

SiCl4:
Silicon tetrachloride (SiCl4) has a tetrahedral shape. A tetrahedral shape possesses a C3 axis but does not possess a C4 axis. Therefore, SiCl4 does not contain a C4 axis and a σh plane.

XeF4:
Xenon tetrafluoride (XeF4) has a square planar shape. A square planar shape does contain a C4 axis and a σh plane. Therefore, XeF4 contains a C4 axis and a σh plane.

GeH4:
Germane (GeH4) has a tetrahedral shape, similar to SiCl4. Just as SiCl4, it does not possess a C4 axis and a σh plane.

[PO4]3-:
Phosphate ion ([PO4]3-) belongs to the point group of Td. Similar to SiCl4 and GeH4, it does not contain a C4 axis and a σh plane.

In summary, the species that contain a C4 axis and a σh plane are XeF4.

To determine if a species contains a C4 axis (also known as a four-fold rotation axis) and a σh plane (also known as a horizontal mirror plane), we need to analyze their symmetry elements.

A C4 axis refers to a rotation axis that divides a molecule into four identical parts by a 90-degree rotation. A σh plane is a horizontal mirror plane that bisects a molecule horizontally.

Now, let's evaluate each species mentioned:

1. [ICl4]-: To determine if [ICl4]- contains a C4 axis and a σh plane, we need to analyze its symmetry elements. However, [ICl4]- is not a molecular formula but rather an ionic formula. Therefore, we cannot assess its symmetry elements.

2. SiCl4: SiCl4 is tetrahedral in shape, which means it does not contain a C4 axis or a σh plane. Its symmetry elements include a Td point group with a C3 axis, but not a C4 axis or a σh plane.

3. XeF4: XeF4 is square planar in shape. It contains a C4 axis since a 90-degree rotation around the central Xe atom brings it back to the original position. Additionally, it has a σh plane that bisects the plane of the molecule horizontally. Therefore, XeF4 contains both a C4 axis and a σh plane.

4. GeH4: GeH4 is a tetrahedral molecule, similar to SiCl4. As mentioned earlier, tetrahedral molecules do not possess a C4 axis or a σh plane. Thus, GeH4 does not contain both a C4 axis and a σh plan.

5. [PO4]3-: [PO4]3- refers to the phosphate ion. To determine if it contains a C4 axis and a σh plane, we need to analyze the symmetry elements of the ion. The phosphate ion does not possess a C4 axis or a σh plane. It has a C3 axis (trigonal symmetry) and a σv plane.

Based on the analysis, the species that contain both a C4 axis and a σh plane are XeF4.